Try 'Buttons for RW Rooted Archos' app from the market.
Buttons for RW Rooted Archos
This application for advanced users requires an Archos 43 / 70 / 101 with an rw rooted ROM (search the web for: rw root gen8), but NOT Urukdroid. If you have Urukdroid or a non-rw root, this application will not work--the changes you make will not stick.
Buttons for Archos will let you change the width of the buttons on the bottom or right of the screen (or remove them entirely if you wish, by setting the width to zero) as well as to rearrange the contents of the buttons.
You can even add new buttons with contents like "Camera" or "Volume +". These buttons should work, but they will have no icons due to limitations in the OS.
It says will not work on urukdroid.It works fine on my Urukdroid 1.5(A70S 8gb) .Change the width to '0' and the soft key button menu bar will disappear after reboot.I reboot several time the changes is still there.