Can anyone tell me how to turn off PID in marlin . The extruder hot end heats up to 200 and cannot go any further after that. i have tried using lot of PID auto tuning , but its of no use. Moreover the temperature rises very very slow

See my post in the other subforum where you posted the same topic.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

If you do not know how the firmware and / or the temperature control works then you should not try to compensate you lack of understanding by completely ruining the system.
Let me guess, if you have a faulty light bulb in your home you first rip out the wiring from the walls to check if that runrs the light on?
Did you consider the most obvious reason for your problem?
Like: You bought a printer that is only rated by the manufacturer for PLA and nothing else?