You can use the "Clear Private Data" button in the Firefox Settings screen to remove your history along with your cookies, saved passwords, etc.

Or you can use this add-on if you want to clear only your history:

https://addons.mozilla.org/en-US/mobile/addon/cleary/

i don't use firefox on android myself, but according to this page:

"To clear your private data in Firefox for Mobile, swipe left and tap the Gear button to access the Clear Private data setting. "

thanks madperson ....that worked