How to Delete COM Ports In Use

Step #1
Click Start > All Programs > Accessories and then click Command Prompt.

Step #2
Type set devmgr_show_nonpresent_devices=1 in the Command Prompt and then press Enter.
(you might have to restart your computer after this)

Step #3
Type cd \Windows\system32 in the Command Prompt and then press Enter.

Step #4
Type start devmgmt.msc in the Command Prompt and then press Enter.

Step #5
Click View > Show hidden devices. This will display devices that are not connected to your computer.

Step #6
Now if you expand the section on COM ports, all the COM ports that have ever
been created will be displayed, the non present ones being in grey. You can
uninstall away anything that you don want (right click, select uninstall).