How to Enable/Disable Roundcube Webmail on cPanel/WHM Server
How to Disable Roundcube Webmail on cPanel Server
Note : Roundcube Webmail will be disabled for all domains on the server if you do the below steps.
1. Login to WHM (Webhost Manager) using server root login details
Link to access WHM : https://yourserverIP:2087
Or
Link to access WHM 2 : https://serverhostname:2087
“yourserverIP” in the above link should be replaced with IP address of your WHM server. “serverhostname” should be replaced with actual hostname of your WHM server.

Link to Access WHM
2. Enter server root login details to access WHM.
username : root
Password : Enter Server root password

Login to WHM to Disable Roundcube webmail
3. Search for “Tweak Settings” in WHM search window and click on it.

Click on Tweak Settings
4. Disable Roundcube webmail in tweak settings. Under “Mail” tab you can see “Enable Roundcube webmail” change this option to “Off” to disable Rouncube webmail for all cPanel accounts.

Disable Rouncube Webmail in Tweak Settings
How to Enable Rouncube Webmail for all accounts on a cPanel/WHM Server
By default Rouncube Webmail will be enabled for all cPanel accounts. Do the below steps if roundcube webmail is disabled serverwide.
1. Login to WHM
2. Search for “Tweak Settings” in WHM search box
3. Click on “Mail” tab under “Tweak Settings”
4. Change “Enable Roundcube webmail” to “On”
This will enable roundcube for all cPanel accounts on your server.