I have a sig 2000 dryer which started making high pitch screech noise.
I had replaced the belt tenssioner pulley assebmly and felt on the door.
In the back some rust is coming from the center of the panel.

I want to remove the drum but don't know how. Please help.

Actually it makes little sense to remove the drum. You have to remove almost everything inside the machine to do so. Economically a bad procedure, as a new machine cost less than a new drum plus labour repair time.

If you insist : have a full service manual available (available from sears service).
Note down all wiring data while you remove. Do not trust your memory!
Disconnect every item till the dryer only consists of dryer housing and drum with bearing assembly.
Disconnect the bearing.
Now open up the drum housing and remove. You may have to remove some welds first.

Of course you can always come back to the board if you run into problems, or to discuss your findings!

Success !

:)