Please follow the below steps to change the login password of NSX.
1) Login on the VC with the user name and password
In my demo lab my VC IP is - 10.0.0.10
Hence the URL would be :- https://10.0.0.10/vsphere-client/?csp
2) Click on Home - Networking and Security and click on NSX edges on the left hand pane.
3) Select the edge for which you want to change the login password and click on Actions on the top.
4) From the drop down action menu select the option - Change CLI credentials.
5) In the Change CLI credentials option, enter the new password for the NSX..
6) Login to the NSX edge with the new password.