Hi, Alexandra -
Welcome to Apple's Discussions.
It is not necessary to use a program to remove OS 9. All you need do is drag the OS 9
System Folder (
not the folder named
System - that's OSX) to the Trash.
You may get a protest from OSX that the System Folder is in use, and so can not be thrown away. If that happens, then drag the file Finder out of the System Folder and onto the desktop, then trash the System Folder. You may need to restart after removing the file Finder to the desktop.
Once the System Folder has been discarded, you can also throw away the folders
Documents and
Applications (Mac OS 9) - those are used by OS 9, and not by OSX. Be sure you have removed any files from those that you need.
In some cases there may be an application in the Applications (Mac OS 9) folder that is used by both OSX as well as OS 9 (this is doubtful in your case, especially if you have never used OS 9). You may want to test for that by placing that folder in the Trash, but not emptying the Trash. Then test run your usual programs - if all is okay you can empty the Trash.
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Note - removal of OS 9 will also remove any capability to use Classic.
Good luck -