With EasyBCD you can edit your boot options to remove the Windows 7 one. You could also go to Control Panel -> System and set the time it displays that screen you showed in your post so that it's something like 1 second with the default Windows 10. If you use EasyBCD, you could then completely remove Windows 7; if you use Control Panel->System, you'd have to leave it, but you could shrink the partition and reclaim the space.
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Good luck.
so... im finally getting around to asking about this, maybe the new operating system has me inspire. how do i get rid of this startup screen: http://i.imgur.com/ZjyMRy0.jpg a little back story;
i used to have one hard drive, a typical old stile HDD. it housed my windows 7 and all my data. then i got a SDD. i installed 7 on it. i deleted all the windows stuff off the HDD (i thought) and forever on i was greeted with a "which 7 do you wanna use" screen on my pc forever since. now with 10 i have the same problem and this screen pops up.
My question is how to I scour that windows 7 instance off the face of the planet?!

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