Clean Activity Folder

Mu iPhone is almost full. To free some space I checked the applications and found out that WD My Cloud is consuming around 25gb of memory. The folder Activity has a lot of files. I am afraid of erasing them because I don’t know if it will affect my files on the WD My Cloud. Otherwise, I tryed to use the option Edit / Clear All but nothing happens.
Could someone help me?

Hello,

Have you tried clearing the cache of the phone?