I don't think so.
To be honest I am a little confused by the original statement "so as I always do, I removed actuals and then tried to remove the assignment" in the context of "actuals were posted" as I always thought a posted timesheet was it, once that happened a whole bunch of referential integrity things stop you from "undo-ing" the work.
You could adjust the timesheet (but that doesn't help as the original timesheet still exists) - so all you can do is remove the resource's "time entry" rights against the project, un-allocate them from the project for any periods that they have not had a timesheet (but this doesn't help much, just being tidy).
If the OP really wants to remove a resource - they can't ; you can obfuscate the resource details/ids so it looks like inactive-junk, but never remove (delete) that record at all.