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

        1. Go to the Suppliers Management page;

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

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

        4. Move the enabled button to "ON"  press the Update button.

Now the supplier is active and available.