if forget itc calim in GSTR-3B and set off Tax Liability

u can use it as credit against gst tax 

Yes...
If you paid as CGST and SGST module then yes...

my question electronic cerdit ledger Debit amount again cerdit ?

(my question electronic cerdit ledger Debit amount again cerdit ?)
But, your 1st question not says this one then how ll be replying experts and participant's... So, ask clearly then get reply as same...

I think you pay RCM tax as CGST and SGST module. You can't use it then the money in there safe.
So, you can use it. Also we can't pay the amount as CGST and SGST only, not paid RCM head. No more separate payment head in challan....
You can get credit. You want adjustable to any other head do it. If not claim it as Refund....