There is two ways to do most things in BUZ and De-activating and Re-activating price grids is no different.
Single Grid
How to get there
If you are logged in to BUZ this link will take you to the Price grids
Settings → Inventory Settings → Price (or Cost) Grids
De-activate a grid
This is the simple way to de-active a grid, although if you want to do multiple grids it might be quicker to use the Import/export function
...
the “Include Deactivated” tick box
the grid you wish to re-activate
Activate
...
Import/Export Function (Multiple Price and/or Cost Grids at once)
You can only Add, edit and De-activate Grids in this method, you are not able to Re-activate a Grid
Go to the Import/Export tab
Download the current Price and/or Cost grids
Make the required changes or additions
Save and upload back to BUZ
...