Yes, you can unsubscribe a phone number from a specific group or all of your current groups. If you would like to unsubscribe a number from all groups, including any future groups, take a look at the suppression list.
Step 1: Select the Group
If you want to unsubscribe a phone number from the known group they are in, then select the group in the drop down menu on the top left.
Step 2: Go to the "Contacts > Unsubscribe" Page
On this page, you can paste in your phone numbers and remove them.
Insert the phone number(s) you wish to unsubscribe from this group or all groups. You can separate them by a comma or a new line.
This is the label you give to these particular unsubscribed contacts.
Delete from all lists/groups?
If YES is selected, then this will unsubscribe these phone numbers from all of your groups and they won't receive any messages from your existing groups.
If NO is selected, then this will unsubscribe them from the group selected.
Step 3: Click Unsubscribe to Process
After you click unsubscribe, this will remove the phone numbers if they are found.