Regularly cleaning and performing some basic maintenance on your extruder will help to maximise the lifetime of this hard-working part of your printer.
Do not attempt to remove cold plastic from the tip by scraping or cutting. This will likely damage the printer nozzle. - If your extruder nozzle is heavily soiled with baked on plastic or excessive residue has built up inside that causes blockages, you may have to replace your extruder nozzle. Find out more in this article.