It's impossible to tell exactly how long it will take signs of marijuana use to leave your system. It usually takes anywhere from 3-30 days to no longer be detectable in urine, though this can go up to 90 days for heavy users. Faster metabolisms take less time to "detox. "
The length of time needed to get THC from smoking marijuana is dependant upon the use. Someone who smokes daily and several times a day it may take up to 45 days. Less use a safe estimation would be at least 30 days. There are many "home remedies" some say can speed the process but trust time and no smoking.