In WHMCS, you can deactivate a pricing slab by following these steps:

1. Log into WHMCS:

   Access your WHMCS admin panel using your administrator credentials.

2. Navigate to Domain Pricing Slabs:

   • Go to "Setup" in the top menu.
   • Click on "Products/Services."
   • Select "Domain Pricing."

3. Locate the Slab to Deactivate:

   • Find the pricing slab that you want to deactivate in the list of existing slabs.

4. Edit the Slab:

   • Click on the name of the slab you want to deactivate.

5. Deactivate the Slab:

   • In the slab details page, you'll see an option called "Status" or "Active". Toggle this to "Inactive" or select an equivalent option indicating deactivation.

6. Save Changes:

   • Click the "Save Changes" button to deactivate the pricing slab.

The slab will now be marked as inactive and will not be applied to any clients or resellers.

Please note that if this pricing slab was assigned to any clients or resellers, their pricing will revert to the default pricing or the pricing of their new assigned slab. Make sure to communicate any changes to affected clients or resellers if necessary.