My understanding is that methamphetamine metabolites are detectable for several days after your last dose. The longer it has been since you used the better your chances are of testing clean. If you do test positive than your best best is to say that you were sick and took decongestants that must have caused a false positive and ask to be retested and hopefully you will pass that one. Not to get preachy but meth is really bad stuff. Either way you should use this as a reason to turn over a new leaf and quit using it.
Detection time for meth (in a urine test) is about 48 -72 hrs but it could be more depending on your level of use. (It is MUCH longer for a hair test, but that is seldom used.)
Not using it is a good way to get it out of your system. I dont think there is any other way, it just has to work its self out
Lay off the pipe...