A bit of a logical dilemma, eh? Normally we would write 'delete where appropriate', i.e. delete in cases where deletion is appropriate. If the deletee (to coin a word) is an inappropriate phrase, however...hmm.... I think the better part of valour is to write your intention out more completely:
Delete [word or phrase] where you consideer it appropriate to do so.
Delete where the [word or phrase] is inappropriate.