I don't know if it's a mine problem, but I can see that the first actions I created, set up for repeating periodically, REPEAT PERIODICALLY! :-D
The problem is that I tried to cancel them since march, without success. I tried by web, phone app, pc app and the result is everytime the same, I find these activities every holy month. It seems like it's impossible for me to recall the original task and deactivate it.
The task is 37d08de0-a50e-11e8-983b-279f0dda2392, but I've also 3 more with the same problem.

Thank you, best regards.