bcdedit /enum firmware
Export boot list and make backup
bcdedit /export newbcd
copy newbcd bcdbackup
Copy identifier of unused entry and delete enty with
bcdedit /store newbcd /delete {98ce75be-453a-15e9-ae7d-c79a86e4d59b}
After you removed all the wanted, save
bcdedit /import newbcd /clean