I think that's easier said than done though. She said herself in the documentary that before she ever had social media she was happy and confident, but she HAD to have it for X Factor and if you are made to have it, there is literally no getting away from the trolls. For many young artists, social media is essential for building a profile and a loyal fanbase. For most of the early part of her career she wouldn't have been able to take a break from it as they never stopped working and it has had a devastating effect of her self esteem and self image, and now she finally the choice to step back she is stuck in a cycle of needing the validation that the positive side brings, but also seeking out the negative to reinforce how she feels about herself.
It's like a drug, and she is an addict and like most addicts, they know it's a destructive cycle but they can't break it. Getting treatment, especially right now will be difficult, and unless she has someone with her to hide her phone(s) 24/7 it's inevitable she's going to keep on posting.