How do you clear a misdemeanor warrant?

Warrants don't "turn into" something different. When a warrant is issued it is either issued for a misdemeanor or a felony offense. It doesn't change.

If you were charged with a felony - appeared in court - the charge was reduced from a felony offense to a misdemeanor offense - and then you skipped out and it has been necessary to issue a warrant...

Only if the state it is issued in has a statute of limitations on the crime itself.

It last up to about 5 to 7 years

Arrest Warrants never expire. They exist until canceled by the judge.