You can delete a single allocation, all allocations from a group on a given day, or a whole series of repeated allocations. Deleting an allocation never deletes the time tracked on it. That time stays in the Time report.
How to delete an allocation
Click the allocation to open its detail.
Click the Delete button (bin icon).
If the allocation is repeated or planned for several people, choose what to delete:
This allocation: only the one you clicked
This day, all users: all allocations from this group on the selected day
All occurrences: the whole series. Allfred then asks whether to delete all allocations, or only this and the following ones.
Deleting a repeated allocation from a specific date
To delete a series only from a certain date, open the allocation on the date from which you want to delete it.
Example: You have a repeated allocation from January to December and want to delete it from July onwards. Find the first July allocation in Planning, click Delete, select All occurrences and then This and following. Allocations from January to June stay unchanged.