This will involve 3 steps:
1) Uninstall the old driver from Device Manager (see uninstall below).
2) Delete the Digi related old oem*.inf and oem*.pnf files (see Digi Clean below).
3) Free up the previously held com ports (see phantom port removal below). This step is only necessary if the com port numbers cannot be reused after installing a new driver.
In the device Manager find the PCI or ISA card under "Multi-port serial adapters". Right click on the adapter and choose the uninstall option. Some Digi adapters with older drivers installed will be listed under the Network adapters heading.
If you are planning to install another driver version, you need to run one of the *.cmd files that will come with the new driver. The appropriate file will depend on the type of product you are using. The below list will explain:
dgclean.cmd: for Acceleport Xem, Xr 920, C/X, Xe)
dgcbcln.cmd: ClassicBoard and Digi Neo cards
dgarcln.cmd: Acceleport RAS cards
dgaxcln.cmd: Acceleport Xp cards
Phantom Port Removal