Banks have established processes for changing signatories on business bank accounts, including in situations where a past signatory is no longer with the business.
In a nutshell: if a past signatory was a regular employee, it just takes any other signatory to remove them. If there was no other signatory, or if the past signatory was an officer, it takes a current officer (as set forth in the company's AOI or corporate minutes). Usually only the latter 2 situations of the 3 above require an in-person visit to the local branch office, and that only requires a few minutes.
I just tried to open the context menu in Windows Explorer. It showed up almost as soon as I released the mouse button, and I have a much slower CPU, older video card, and way less RAM then you do. I was also running 12 windows of Firefox with collectively 1000+ tabs (though only about 36 or loaded), Steam, a Unity game, and Microsoft Teams, plus a number of background programs.
If your Explorer context menu is taking more than a split second to load, there's something wrong with your hardware.