Once you open Mobile Self Service Application, you will have to enter your "(1) UserID" and your"(2) Password" , then click on (3) Sign In to login into Mobile Self Service as shown below.
Once you login into Mobile Self Service, you will be redirected to Duo setup page where you have to click on (1) My Settings and Devices.
You will be redirected to Authentication method page where you will select any one authentication method as shown in "(1)"
If you have selected "Send Me a Push" , you will be shown a message (1) Pushed a login request to your device .
You will get a notification message on your Duo Mobile App, click on (1)"Approve".
After successful authentication, you have to select "(1)Device Options" to see the details of device which you wish to remove.
Click on "(1)Delete Icon" as shown below.
Click on "(1)Remove" as shown below.
You will get (1) Successfully removed device message as shown below.