Lock a sheet
You can also lock a particular sheet to be made inaccessible to edit for other collaborators.
To lock a sheet
Click Data > Lock> Lock Sheet.
Lock the sheet to those collaborators for whom you wish to lock the cells. The sheet stays locked to newly shared collaborators as well.
You can also lock the sheet by right clicking the required sheet and using the context menu.
You can unlock both cells and sheets in the same way you had locked them. Select the range of cells that you wish to unlock and click the Lock icon near the collaborators to unlock the ranges or sheets.