The only reason a bank account will show in the list of potential bank accounts is if the program thinks it is a bank account.

Under the Chart of Accounts, you can open the ledger for your bank account and select the Class Options tab.  Check here to see if it is still listed as a Bank Class.

In the image below, you do not have to include your bank account information, just the class.  This is from the sample file.

It is set to the Bank Class.  

It is set to the Bank Class.  

I just tried to get it not to show but I can't.  I would suspect it has been linked to some other part of the file but I can't figure out what would remove it from the drop down.  I tried to link to Inventory Adjustments, Customer, etc. and it still showed as a bank account in the list.

You may wish to follow this article from the Knowledgebase to see of it helps, assuming you can't find where it might be linked going through the setup menu Linked Account options and the Inventory and Services List report (showing linked accounts).

Please make sure you get a backup of your file before doing what the article suggests.