Sorry mate, I'm not 100% sure if the Galaxy S7 Edge does have a Recycle Bin Feature or not as I started with the Galaxy S2 then upgraded to the S4 then didn't upgrade again until the S9+ came out as the S4 was and is an awesome phone.....I still have/use the S9+ now as it's another awesome phone just like the S4 !!
Anyway, Sorry I digress.....IF the S7 Edge does have a Recycle Bin you need to turn it On before you can use it !!
Simply open your Gallery App, then tap the 3 Dots near the Top-Right Corner, then tap Settings, then somewhere near the bottom of that menu you should see an option to Turn-On the Recycle Bin, simply turn it on and Viola, everytime you try to delete something it'll go in the Recycle Bin for 30days !!
BUT, If you don't see an option to turn it on in there, then unfortunately you don't have one built-in.....If that's the case, then you should be able to Install one from the Galaxy Store, as far as I know the one that's built-in to the newer Galaxy Phones isn't available for download but there are other 3rd Party ones there that should work and do just the same for you, simply search for 'Recycle Bin' in the Galaxy Store and have a read of each one's description and read other users reviews to decide which is best for you and your phone ok !?
I started with the Galaxy S2 then upgraded to the S4 which I had until the S9+ came out as the S4 was and is an awesome phone, now I'm sticking with the S9+ for a while as it's another awesome phone like the S4 !!
Anyway, Sorry, I digress.....I'm not 100% sure if the S7 Edge does have one or not, as I said, I jumped past the S7.....But, if it does have a Recycle Bin then it needs to be turned On before you can use it !!
Simply open your Gallery App, then tap the 3dots near the top-right corner, then tap Settings and IF you have a Recycle Bin the option to turn it on should be near the bottom of that menu, scroll-down and hopefully you'll find it !!
If you don't have the option there then unfortunately you don't have one built-in BUT you should be able to Install one from the Galaxy Store !!
As far as I know, the actual Samsung version that's in the newer phones isn't available in there but there are 3rd party ones that should work just the same, simply search for 'Recycle Bin' and have a read of each ones description and other user reviews to see which one best suits your phone your needs !!