i lost my backup disk and i cant remove it from time machine and i cant add a new one either. not even in options

Give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

Another possibility is to hold down the Option key when accessing the Time Machine menu and select the "Browse other backup discs…" option:

See if that will let you access the drive and then try making a backup if successful.

Try disabling Time Machine, then select the drive. You should be able to click the minus sign to remove it.