Go to your doctor and tell him/her you want to wean - don't do it by yourself! At least call them -
~If you are 20 mg tabs, then for 7 days take one every day
~then cut the tabs in 1/2 (10 mg) and take one of those for 7 days
~then cut those in 1/2 (5 mg) and take that for 7 days
~the final week take one 5 mg tab (1/4 of your 20 mg tabs) every other day for 7 days.
Thats the jist of what he or she will tell you to do. They need to know you are weaning though in case you do have some withdrawel symptoms and need medical attention.
I was on Lexapro for 6 months before I weaned off - like others on here I hated feeling dependant on medication. I didn't have any withdrawels what-so-ever. My advice though with any selective seretonin reuptake inhibitor to be careful. Bluntly speaking when you start messing around with the chemicals in your brain it gets really confusing and should only be done with the supervision of a licensed health professional
Good luck