We have created an user with name admin and with some password. Now we forgot the password and want to reset it but the password field is disabled as shown in the attachment. But for other users it is fine. How to reset password for this user with name admin. capture.png
That admin user is something that is created by default. You can edit it by going to file where passwords are stored. They would located in <DT_Home>/server/conf/user.permission.xml
If you remove the password attribute from the <user userid="admin"> entry (make sure to stop the server before editing and start it afterwards) you should be able to login without any password.
You can also delete the file and restart the server. This will create a standard file and and the password would be reset back to default (which is 'admin') but I would recommend trying the first approach first.