it's an interesting task where you can experiment with new ideas. For example, 'when record matches condition', If you have empty links in Tasks, Allocations, and modified day of that field different from the day of record creation, it may be your case with removed Project
There is no way to monitor for record deletions in Airtable unless you know how to write your own custom programming code and you can figure out how to use Airtable’s extremely complicated webhooks API.
The much easier approach would be to just add a checkbox field (or a single select field) that the user selects when the user wants to delete a record. Then, when the user checks the box (or selects an option), that would trigger the automation to delete records everywhere.
There is a small learning curve with Make, which is why I created this basic navigation video to help. I also provide the links to a few other Make training resources there as well. For example, to instantly trigger your Make scenarios from Airtable, check out this thread.