Format > Area

Lock

Locks an area in the worksheet. You can lock the area with or without a password.

Unlock

Unlocks a locked area. If the area was locked with a password, Mathcad prompts you for it.

Collapse

Collapses an area in the worksheet. The area boundaries and the regions between them collapse into a single bar which you can move, but which you cannot delete or copy.

Expand

Expands a collapsed area. The collapsed bar appears as two bounding bars, and regions in the collapsed area appear.