I'm very impressed that your children have been taught some Latin! It's great that you've taken some advantage of the fact that children can pick up languages with relatively little effort up to the age of seven or so.
With regard to your various commands and wishes for your children, here are some translations:
Go clean up your room:
agite liberi, cubicula vestra componite!
N.B. "agite" is a word that I think you might find rather useful with these translations. It has the equivalent of English "come now," which often precedes imperatives. The singular would be "age".
I am ignorant of your children's genders, so I keep the vocative ambiguous with "liberi"=children . If you want to be more specific: boys = "pueri"; girls = "filiae"; or you = "vos"; there are more poetic alternatives!
"Compono" is the closest word for "tidying" - a concept without a proper word for the aristocratic and slave-surrounded Romans whose language survives! It has the sense of "put things in their right place"
Additionally, "vestra" means "your" but in commands such as these it is very often omitted, as confusion of possession is rare in such situations. In the following translations I have omitted it.
Brush your teeth.
(detergo is a nice verb that has the perfective lexical meaning (or, more technically, aktionsart) of "wipe/brush" clean, so the order implies that the brushing should not just begin, but be carried through to completion!
Time for your bath!
nunc tempus balnei est.
"balnei" (or "balinei") is effectively an objective genitive, which qualifies what the purpose of the time is, namely a bath. "nunc"could plausibly be replaced by "hoc" - this. I think a more elegant alternative would be the use of the gerundive, but unless your kids are phenomenal prodigies and your teaching is extensive this suggestion is only to placate me! viz. "nunc vobis est abluendum".
Clean up your plate.
My rendering is dependent upon my (perhaps incorrect) interpretation of the English. Over here across the pond, the phrase has more the sense of "finish off the food on the plate [and thus make it clean]" as opposed to "wash it up". I'm not sure which one you mean but I've gone for the former as opposed to "catillos purgate" or somesuch phrase;
"agite, cibum peredite" (come now, finish off eating [your] food)
Let's go outside.
Finally, after all the imperatives comes a jussive subjunctive! Once more, I'd be very impressed if your children know the subjunctive mood! Nonetheless:
would do the trick.
Hope these are of use!