So much frustration. But there is help, please read:
1.) You can turn off "Your memories from this day." Go to OneDrive via your browser by going to https://onedrive.com and signing in. (This is just another way to see you OneDrive files, accessible from anywhere in the world with internet access and a computer.) In the upper right click the gear icon for Settings. Choose Options. Then choose Notifications. Uncheck the item for memories!

That will stop the emails. Yay!
2.) You were getting memories of pictures which you don't want to see. Even if you turn them off, this is not a good organization!
You can choose which folders are synced, which are only local and which are only in the cloud. Let's say you like getting the memories, but not the work or whatever pictures. You can segregate the pictures. Don't leave them all in one folder. This may take some time now because you didn't set up organization of folder previously. You can create a new folder (OtherPix in my example). It can be under Pictures, or as C:\OtherPix. Then TURN OFF SYNCING for that folder. Or folders. To do this:
- Right click the OneDrive cloud icon in your task bar at the lower right of your screen.
- Select the gear icon in the upper right for Settings.
- Choose Account tab.
- Click the Choose Folders button
- Expand the Documents folder and note the Pictures folder
- Expand the Pictures folder
- If you created the OtherPix folder under Pictures, UNCHECK it. Now that folder will not be synced. Make sure there are local copies of the pictures first.
- You can now go back to File Explorer and move any pictures you don't want to see in memories (if that was your preference) to the OtherPix folder. They won't be available for Memories to find.
They may appear to be deleted, but they are not. You moved them to a non-sync'd folder. Deleted from OneDrive. You can also save a copy to OneDrive and delete from your computer local storage. You have options here. You can create a folder as the only one OneDrive uses for Memories. Stop syncing all the others.
There are details to learn and I may not have given all you need. I hope I have given a hint. I do find it a problem that Microsoft has changed the way SkyDrive, OneDrive whatever works over the years. Maybe it will stay stable for a while.