OneDrive / Android automated camera roll back up without sync

Hello I am unsure if this is a Microsoft or Android issue so apologies if this isn't the place. 

I wish to have my Android (s21) camera roll automatically back up to OneDrive but without the two syncing together. 

If I wish to delete a photo from my phone I do not want this to delete from OneDrive but currently they do and I cannot find a solution to just have the camera roll back up without the sync in place.

Is anyone able to produce a dummies guide to achieving this as I am not grasping other instructions I have found online.

Many thanks for any assistance.