Locking a plan protects its setup from accidental changes once it's been finalized. A locked plan stays fully active – you can still view it and work with entries in your views – but its core settings and entry tags are protected.
How to lock a plan
Go to the Plan Setup page of your plan.
Scroll to the bottom and click Lock plan settings.
To unlock, follow the same steps and click Unlock plan settings.
What you can't do while a plan is locked
Edit the plan's main info or dates
Edit the plan's custom fields
Delete the plan
Edit tags on the plan's entries (unless the tag category has Allow editing when plan is locked turned on – see Tag settings)
You can still add or remove users on a locked plan at any time.
Who can lock or unlock a plan
Lock: Admins and Editors
Unlock: Admins, or the person who originally locked the plan
A few things to know
Locking is set per plan – there's no option to lock all plans in your organisation at once.
Locking is not the same as archiving. An archived plan is taken out of your active views, while a locked plan stays active but has its settings protected.