I have phantom serial ports in Windows XP. How can I remove them?

The first step of removing the phantom ports is to remove all non-standard COM ports (remove any Multi-port serial adapters from the device manager).
Most likely there are leftover entries in the registry. You can run regedit to remove the extra entries.
NOTE: make a backup of the registry prior to taking any of the following steps. You edit the registry at your own risk.
Run regedit. Go to: HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/COM Name Arbiter
Your system probably has:
The Data field of COMDB = FF FF FF 03 (or something similar).
It should have:
COMDB = 03 00 00 00, if you have 2 built-in serial ports (or 01 00 00 00 if you only have one built-in COM port).
NOTE: 03 in binary is 0000 0011 so the lowest bit set (the 1 on the right) means COM1 is in use, and the bit to its left, in the 2 position, means COM2 is set.
You will also want to clean keys for any non-standard serial ports from these places:
HKEY_LOCAL_MACHINE/HARDWARE/DEVICEMAP/SERIALCOMM
HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows NT/CurrentVersion/Ports
You should be able to power down and reinstall the Digi adapter if it had been removed from the system. If it is installed, reboot the system. The adapter should be redetected and the driver installed. The com ports should now default to start at COM3 (or COM2 with only one built-in serial).

移除幻影端口的第一步是删除所有非标准的COM端口(从设备管理器中删除任何多端口串行适配器)。您可以运行Regedit来删除额外的条目。
注意：在执行以下任何步骤之前，对注册表进行备份。您需要自行编辑注册表。
运行Regedit。转到：HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/COM名称仲裁器
您的系统可能有：cmdb=ffffffff03(或类似的内容)的数据字段。
如果您有2个内置串行端口，则应该有：comb=03 00 00 00(如果您只有一个内置的com端口，则comb=01 00 00 00)。
最低位集(右边的1)表示Com1在使用中，左边的位表示COM 2被设置。
您还希望清除这些地方的任何非标准串行端口的键：
HKEY_LOCAL_MACHINE/HARDWARE/DEVICEMAP/SERIALCOMM
HKEY_LOCAL_MACHE/Software/microsoft/WindowsNT/CurrentVersion/Ports
如果Digi适配器已从系统中移除，则应该能够断电并重新安装它。
如果已安装，请重新启动系统。应重新检测适配器并安装驱动程序。
COM端口现在应该默认从COM 3开始(或者COM 2，只有一个内置串行)。