removing soldered on chips from circuit board?

you're just going to need a higher Wattage soldering iron. You can use a heatsink attatched to above the pins before the actual chip to avoid burning. You can place a strand of meshed copper wicker to absord the solder as you melt it. Still to avoid burning, I would suggest only doing it a little at a time per pin just enough to melt and absorb the solder. This is going to be a little tricky depending on your experience. Just be careful and follow the steps I gave and you should be fine.

If the board is double-sided or multi-layered you will find it very difficult to remove the through-hole components (where the component pins or leads go through holes in the board). The reason is that each hole is plated-through, so however much solder you remove there is nearly always some solder sticking the component lead to the plating. With 2-lead components it's not such a problem because you can just lift the end of the component as you melt the solder in the hole. With chips it's harder. The best way is to suck out as much solder as possible with a solder sucker then grab the protruding leg with fine-nose pliers and wiggle it until it comes loose. Repeat for all legs then pull out the chip. Surface mount components are something else. Basically, don't even try! You really need a special soldering iron that is specially shaped to melt the solder on all the pins simultaneously.

just tough them with a hot soldering iron

There is a special iron for that. A regular iron will work, but the logistics are tough. Alot of wiggling there.

use some tweesers and carfully remove it