Hi all ive just been give a cuple of space marine bikes painted and used,but i wonderd can i take the space marines and use them as looted bikes if so whats the best way to remove the marines

Yes you can , but the idea of looting generally means you have to do something with them.
Easiest thing is to extend the front axel away from the bike (to make it an easy rider... much more orky to be on an easy rider) and stick ork weapons in the gap *crudely*)
Heres another thread of bashes http://www.librarium-online.com/forums/ ... log-3.html
And I'm sure ork mod guy could off top of his head think of some good orky tweaks.
Removing the marine? if its plastic glue and he has become part of the seat... you'll have to saw him up (saw him up very roughly so you don't have to hurt the bike..you don't care about the marine.. you care about the bike) saw his torso in two to get a better angle at the rest of him, have a wiggle with a pair of choppy things on one of his legs (if he holds fast and he's melted on reevaluate..hacking at it might become dangerous because of the force required)Be prepared for none of the handle bars to survive.
Super glue model over 2 years old?he should just snap off fairly easily.
Fluff wise- the people who loot lots are the dethskulls with their blue paint scheme.. If you want props and a good rep from friends keep all this stuff in the back of your mind http://wh40k.lexicanum.com/wiki/Death_Skulls

Thanks for the advice can i just ask what moderls are thous bikes in the pic

I believe they are bottle caps or something similar, designed to ape gyroscopic biky things like in star wars3.

There awsome but theyre big bottle caps

From looking at it it seems like the old Ork truk driver seated on the gun/engine block from an ork warbike, inside a slice of 3" drainpipe. The Tread on the wheels look manually made with sections of plasticard and plasticard rivets. On the second bike the spikes are from the old Chaos vehicle accessory sprue (two different sizes).