Now, if we are talking suppressors - I guess you could always use it, take it off when your're done and toss it back in the safe or whatever.
Again, in a very clear cut situation this would probably be a non-issue.
If it's not clear cut, and there is a detailed investigation the fact that you used a suppressor but removed so that its use would not be detected could affect the results of the investigation in a manner that would cause your story to be suspect.
For example, GSR on the person shot is often used to determine if they were shot from very close range. A suppressor will definitely affect GSR significantly and could make it appear that someone was shot from farther away than actually occurred. If that result contradicts your story then you are left with some unpleasant options.
You're better off not trying to alter the scene before the police arrive.