I believe the correct question is :-
⟹ I was very warm, so I _____ my coat. (take of)
Then the answer will be :-
⟹ I was very warm,so I took of my coat.
Step-by-step explanation:-
⟹ Change the verb given in the bracket to past tense ⟶ the word 'was' [past tense] is used in the question.