The TREKINETIC K-2 can stand up without it's wheels on.

So to fold it up, you simply remove the quick release wheels, detach the quick release clevis at the back and fold up the rear assembly. Then just slide up the telescopic footrest and it's done.No tools or tightening is required.
 
The folded up size is about  860mm (34") x 570mm (22") x 470mm (18") and without the wheels it weighs around 9 kg.

An able bodied person can release the wheels and fold the chair up in about 8 seconds.