Hi Hummer, nice to meet you ...
Here are the steps which you can use to free all ports.
1. Click start –> Run –> type regedit and click OK button.
2. This will open a Registry editor.
3. Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\COM Name Arbiter

regedit - comp port
Now right panel , you can see a key ComDB right click to that key and click modify. ComDB

In value Data section select all and delete reset to Zero ‘0’.
click OK
Close Registry editor and then restart your computer. all COM ports are now Free, you may need to reinstall any USB to serial convertor.
Note: It is always good to take back up before deleting any entry from Registry, to take back up for Com Name Arbiter, in left panel right click on COM Name Arbiter and say Export, save with some name and appropriate location.