Do a search on this board or go to pca.org. They've got a huge Q&A section.
But to answer your question since I just removed my stereo last week to put an iPod cable on the back, if it is a Becker just go to
www.beckerautosound.com and find their phone number. Give them a call and ask them to send you the stereo removal keys. Once you get them pop the keys in the slots at the bottom corners of your radio and pull it out.