iCloud is a Synchronization Service-- it makes everything connected to it the same. So if you turn off iPhone's iCloud, delete pictures, and then turn it on again, Photos will just copy all those pictures from iCloud back to your phone. There's no point in turning off iCloud on you phone.
It's your MacBook that will be in control. Does your Mac Photos>Settings>iCloud have "Download Originals" checked? If it does, then all your pictures are there.
(If it doesn't, then you need to switch to Plan B!)
Plan A: With all the pictures safely on your Mac, you could turn off iCloud on your Mac, and then delete all the pictures on your iPhone. All the pictures would also be deleted from iCloud! But they'd still be in the Photos Library on you Mac. So, now you make a new Library for the Mac--close Photos, option click the Photos icon, and choose Create New from the Library dialog.
A new, empty Library will open. You then, on the Mac in Photos>Settings>General, you must make this new, empty Library your System Library. In this picture "Use as your System Library" is grayed out, because it already is the system library. Only the System Library can connect to iCloud.
Then turn on iCloud (and Download Originals.) You phone is now empty, your iCloud Photos is empty, and your new Library is empty. But your pictures are in the Old Library.
You can double click on the old Library and see the old pictures in Photos, but it's no longer connected to iCloud (only the one System Library can connect to iCloud) so they won't be copied to your phone. New pictures from your phone will go to iCloud and be copied to the new Library on your Mac. By double clicking on a Library, you can switch between them any time. Only the new one should be the System Library and have iCloud turned on.
Plan B--this is if you have checked "Optimize Storage" on your Mac's Photos iCloud settings. That means that the Mac may not have copied full sized images from iCloud. It doesn't really have all your pictures. The best thing to do in this case is, hold on, make a new empty Library like above, set "Download Originals," connect it to iCloud. Then wait. Wait some more, and eventually this new Library will fill with full sized images from iCloud. Now you have your old Library--toss it--it doesn't have full sized images, anyway. And now you have a lIbrary that has all your pictures. It's just like at the beginning of Plan A. Depending on the size of your Library, you may have to wait a week or more, but the Library should tell you when it's finished syncing. It might say something like this
at the bottom of the Library view. Leave the MacBook plugged in and running as much as possible--overnight is good. Keep Photos in the background when you're not using it--Photos will slow downloads to keep from interrupting your work.
Now--you're ready to go to Plan A.
This could use a lot of storage space on a disk-- you end up with two Libraries. You may have to have the help of an external hard drive for some of the swapping.
