That must have been a nasty surprise. The resolution of the photo isn’t fine enough to identify the bug and its doubtful there is enough of it left. It isn’t a roach and I don’t see a female structure called an ovipositor. It is probably male, given its size it is unlikely you missed another. Killing it is all that needs to be done and it probably is a bug that lives in decaying plant matter. Discard the old potting media in a tied off plastic bag and dispose of it in the trash. Metro trash goes to the burner. Repot your plant and it is highly unlikely there will be more bugs.