You can control which connection methods each client is allowed to use for sending SMS. By default, all methods are enabled — you can turn off any of them at any time without affecting the client's account setup.
Go to Profiles → Clients.
In the Actions column, click the edit icon next to the client:

In the window that opens, scroll down and find the sending method checkboxes:

Uncheck any method you want to disable for this client:
|
Checkbox |
Description |
|
Can Send via SMPP |
Allows the client to send SMS via SMPP connection |
|
Can Send via API |
Allows the client to send SMS via API |
|
Can Send from Web |
Allows the client to send SMS from the web panel |
|
Can Send via RESTAPI |
Allows the client to send SMS via REST API |
Click Save.
Any method that isn't checked will be unavailable to the client until you re-enable it.