This post mainly tells you some information about Windows boot manager and how to enable and disable it.
Besides, you will get some extra information about it.
It enables you to bootWindows 10/8/7 orWindows Vistaoperating system.

Besides,MiniToolwill offer more information to you.
The database replaces the boot.ini file used in old Windows versions likeWindows XP.
It is marked as Active inDisk Management.

In most Windows PCs, this partition is labelled as System Reserved without harddrive letter.
Should Windows Boot Manager be first?
If you are curious about it, explore the answer from the post.

Actually, you are unable to delete Windows boot manager.
you’re able to utilize the given methods to enable/disable Windows 10 boot manager.
Step 1:Typecmdin the search box, and then right clickCommand Promptand chooseRun as administrator.

Step 2:pop in the following commands in thePromptand hit theEnterkey after typing each one command.
Here are steps for you.
Step 1:Open theRundialog window by pressingWinplusRkeys.

Step 2:Typesysdm.cpland clickOKto continue.
Step 3:When theSystem Propertieswindow pops up, choose theAdvancedoption.
Then press theSettingsunder theStartup and Recoveryoption.

After that, clickOKto save the changes.
What to do ifBIOS show two Boot Manager?
This post offers some clues to you.
Extra Information about BootMGR
The common boot error in Windows is theBOOTMGR is missingerror.
The Boot Configuration Data store is safer than the boot options in previous.
On the contrary, if youre using older versions of Windows, use theBootcfgandNvrBoottools instead.