If you want to use the question mark in NSX Manager CLI, press Ctrl+v just before inputting the question mark.
Example:
1. Switch to Configuration mode.
nsxmgr> enable
nsxmgr# configure terminal
2. Run "enable password".
nsxmgr(config)# enable password
3. Enter your password. In this case, the password is "abc?123".
3-1. Input "abc".
nsxmgr(config)# enable password abc
3-2. Press Ctrl+v.
nsxmgr(config)# enable password abc
3-3. Input "?123" and save the password change, then exit Configuration mode.
nsxmgr(config)# enable password abc?123
Password changed
nsxmgr(config)# write memory
nsxmgr(config)# exit
nsxmgr#