"One account. All of Google" this is okay if we have a clear idea of the products and the data which we were syncing to the device. If not then certainly face this type of problems for sure. So at the time of first login itself should check what all the data is being synced to the device and uncheck if you wish, not to.
So here, unfortunately there is no option to organise the synced Google/G+ photos(Picasa web albums) in Gallery. So how to delete or hide those albums. This is simple and the same to be followed in case of other accounts too.
How to delete synced Google/G+ photos in Gallery?
Step 1 : Goto Settings > Accounts > Sync ( a tap your email ID) and uncheck the Google Photos and Google+ photos.
Step 2 : Again in Settings Goto Apps under Device and navigate to the Gallery app and tap the clear data option.
Now open your Gallery and check for the Albums.
That's it and your done.