A bash script to clear MMS messages stuck in the cache on the Pine64 PinePhone (https://www.pine64.org/pinephone/) running Manjaro-Arm (https://wiki.pine64.org/wiki/PinePhone_Software_Releases#Manjaro_ARM). My PinePhone was the Plasma developer's community edition.
This file was put together via searching forums and trial-and-error. Hopefully the PinePhone community will update the mobile Linux OS to accomodate MMS messages in the future. I found the PinePhone to be unreliable just enough that I had to give it up this summer for now until it becomes more reliable (my current phone is a Pixel 3XL running Calyx-OS Android).
I am posting this hear for anyone who might benefit from it.