When a supplier is disabled, you won't see them in the suppliers' list anymore. However, the supplier has not been deleted and can be re-enabled through these steps:

        1. Go to Supplier Management → Manage suppliers;

        2. Click on Show filters, type the supplier's name, and choose Enable - "No" Filter;

        3. Select the supplier you want to enable click on the Edit button in the Action column; 

        4. Move the switcher on the right side of the 'Edit Supplier' row to enable the disabled supplier (a switcher should be green and show "ON")  Update.

Now the supplier is enabled and available.