This will guide you through adding and removing interfaces from VSAN Database. Even though I have tested this on Cisco MDS 9124, the process is virtually the same on the Cisco Nexus platforms with a slight difference on interface names.
When you issue the command show VSAN membership will tell you which VSAN member an interface is part of.
Interfaces are usually in VSAN 1 being the default and it can be moved to other VSAN by using the following commend.
vsan 100 interface fc1/1
If you want to remove an interface from a particular VSAN, you need to move it back to VSAN 1.