HOW TO REMOVE UBUNTU FROM WINDOWS BOOT MANAGER. 1. Boot into windows then type(ignore the quotation marks) 'cmd'. In the search results that appear, right click on 'cmd.exe' then choose 'run as administrator'. 2. Then type 'dcdedit.exe. A list of operating systems in the boot manager will appear. Notice the ubuntu section of the output and make sure you identify the ubuntu identifier. 3. Then type 'dcdedit.exe/delete {type here the ubuntu identifier exactly as it is} then press enter. Thats that!