Facebook sign in Problem

Hi,

   I have the issue with facebook login , the issue is that when i login to facebook , it show a message that you  can only be connected with one facebook account ,

please help me , how to remove facebook account , This issue is happend because i have one another account of royal revolt , And i have enterd that Facebook ID , which i was using in the 1st Account ,  so after that it shows IMERGE , but i dont want to imerge , i want to use the 2nd one ID , and also want to enter it another facebook account ,

I have Tried to enter it another Facebook account , but it shows the upward image message

please help me how i remove My 1st ID facebook account from my 2nd ID