I need to know if there is a way to delete older income and expense items wo assets and liab

I doubt if you have "too many transactions."  I have about 50,000 transactions in a file that over 179,000 K and it works just fine.  But one method of shrinking the file by pruning older transactions while leaving your balance sheet unchanged is File > File Operations > Year-end copy.  That will archive older transactions in an "archive" file and reduce your transaction count considerably.