It would probably be better to wean off of those medications one at a time. They both affect your central nervous system, so you want to do it slowly.
Also, is there a reason that you are going off BOTH of them? Is your anxiety completely gone? If you are stopping lexapro because you lost your insurance or something, you should talk to your doctor about switching to the anti-depressant citalopram, which is chemically related to lexapro, but is generic and much cheaper.
It's best to discuss the proper dosing reduction for you with your doctor. In general, the dose for both medication are decreased every 1-2 weeks over several weeks or months as tolerated.