You can lock your own timesheet in the Timesheet view by hovering over the desired date and clicking the lock icon:
Make sure you have registered all the actual hours before locking the timesheet
Clicking the lock icon prohibits you from registering actual hours for any project until the selected date:
Only admins of Silverbucket can open the hoursheet lock again
As you click Accept, the fields before the chosen date are greyed out and can you can no longer edit them:
In our scenario (locking the hoursheet until 2020-06-17 the dates circled with red are unavailable; dates circled with green can still be edited
You can also lock hours on a project or task level from the Project's Dashboard; see the project Bridges #2 and task Project Management Duties in the screenshot above for example.
Only admins of Silverbucketcan re-open locked datesfor other users. This can be done by clicking the lock icon on someone else's Timesheet
Admins of Silverbucket can also lock other people's Timesheets in a similar manner after choosing the desired User from User dropdown list.