I’m looking for some advice on using the word “off”.
2 examples:
“Put the kettle on” (Rho’r tegell ymlaen) is the “on” phrase, but how would you say: “Turn the kettle off”.
“Put your shoes on” is the “on” phrase, but how would you say: “Take your shoes off”.
Finally, is there a difference for “Take off your shoes” vs “Take your shoes off” depending on the position of “off” in the sentence, or is there only one way of saying it because the meaning is essentially the same.
Thanks
Things like ‘put on’ and ‘take off’ are what’s called ‘phrasal verbs’ in English - they don’t really have equivalents in Welsh. What I do when I come across one of these is to find another way of saying it in English without using a phrasal verb (so without a verb + preposition), then try to find a word for that.
So with ‘put the kettle off’, to me, the ‘put off’ is the same sort of thing as ‘put off the light’, and another way to English is ‘extinguish’ - the word for that in Welsh is ‘diffodd’ - so perhaps that might work for kettles too? (I have no idea - I don’t think I’ve ever had to say it, since most kettles do it automatically these days ;-))
As for ‘take off’, I tried to ‘remove’, but none of the definitions I could find seemed to fit. So I knew that to ‘put on’ is ‘gwisgo’ and that the ‘un’ prefix in English is often ‘dad’ in Welsh, then I searched on ‘dadwisgo’ - and hey presto, it means ‘unclothe, strip, undress’.
Sometimes learning a language is a bit like a logic puzzle, isn’t it!
Found something useful by @Aran on a post from 2014 (hope thats OK), which I will just paste in here if it helps. Includes put on and take off your shoes.
Rise and shine - amser deffro!
Let’s go out - awn ni allan
Let’s go to the playground - awn ni i’r maes chwarae
Let’s brush your teeth - beth am frwsio dy ddannedd?
Bon appetit (or something similar) - mwynha dy fwyd
Oh my god! - O fy Nuw!
Put on your shoes - gwisga dy sgidia
Take off your shoes - tynna dy sgidia
A phrase that encourages good behavior - like “Listen!” - Gwranda!
Listen to your mother! - Gwranda ar dy fam!
Listen to your father! - Gwranda ar dy dad!
How was your day at school/preschool? - Sut oedd heddiw yn yr ysgol/cylch meithrin?
Take care of your sister! - Gofala am dy chwaer!
What’s this? [questioning what an item is] - Beth ydi hwn?
Sleep well / sleep tight - cysga’n dawel
Sweet dreams - very idiomatic, no immediate thoughts - we just say ‘nos da, cysga’n dawel’
Isn’t it tynnu? That’s what I’d use, anyway. 
I’m sure you’re right - I was going by dictionaries only, and as we all know they don’t always reflect usage! The English there was probably a clue - you wouldn’t ‘unclothe’ your shoes 
The broader point still holds though, I think: the two-word English phrase ‘put on’ is translated by the single Welsh verb ‘gwisgo’. That can be quite a hard concept to get your head around at first.
dadwisgo sounds like a good word. Would something like sgidiau bant work or cer esgidiau bant??? - it might be the wrong sort of off I suppose, but sounds good to me for some reason.
I know a phrase that end in bant! Wouldn’t say it to anyone on here though
I hav always wondered about hold my hand. Could be a range of really colloquial forms here that I don’t know and I feel I should. I’m guessing dal (f)y(n) llaw i, gafael yn llaw i etc, but not sure what’s right here or what to use. This isn’t for conversation or to be understood by the wider world etc, just the most natural command to a child.
If I wanted a child to come down or come here, then I’m happy as Larry with dere ma and dere lawr, but hold my hand has always bugged me.
Dal fy llaw is fine.
diolch yn fawr. It is nice and snappy as well isn’t it
I use ’ rho dy law i mi’ or ’ rho dy bawen … ’ if I’m drying the dog😀
That’s got me singing a Sŵnami song in my head. Thanks.
A finnau 
Troi i ffwrdd can be used, at least colloquially, as the equivalent of " turn off". For example, troi’r cyfrifiadur i ffwrdd. It’d probably be diffodd y cyfrifiadur more formally - but “embrace the colloquialisms” is my (own personal, maybe controversial) mantra
Troi bant in the south, too. I don’t really like it, but find myself using it nonetheless!
The place where I usually use my Welsh the most is at work. I’ve encountered problems with ‘off’ when I want to talk about ‘days off’. To be honest, I haven’t really dealt with it, I usually just work around it by saying something like ‘I will not be in work’ or ‘I was not in work’ when I would like to say ‘I’m going to have a day off’ or ‘I had a day off’. Sometimes I use the phrase ‘amser bant’ (time away?) but I’m not sure this is quite what I’m looking for.
Does anyone here have any ideas?
Probably easiest just to say ‘diwrnod i ffwrdd’… 
So simple! Thanks Aran
Croeso mawr
Bant o waith is what I’d say for off work.