The catroot2 folder in Windows operating systems is not harmful; it is a legitimate process that affects your computer's ability to receive Windows updates. There is a reason to want to delete it, however; files within the catroot2 folder can become corrupt, preventing you from installing Windows updates. Renaming, moving or deleting the catroot2 folder will cause Windows to create a fresh copy of it from protected memory, which will usually fix any installation problems caused by corrupted files.
Click the "Start" menu, and select "Run." Type "cmd" (without quotation marks), and click "OK" to open the command line interface.
Type "net stop cryptsvc" (without quotations), and press "Enter" to temporarily disable the cryptographic service. Wait until the command line interface says "the cryptographic service was stopped successfully" before continuing.
Type "ren %systemroot%\System32\Catroot2 oldcatroot2" (without quotations), and press enter; this will rename the unwanted catroot2 folder to "oldcatroot2", allowing Windows to create a fresh copy of it.
Type "net start cryptsvc" (without quotations) to reactivate the cryptographic service. Wait until the command line interface says "the cryptographic service was started successfully" before closing the interface.
If you're renaming catroot2 in order to fix a problem with Windows updates (the most common reason for doing this), you may need to delete certain temporary files to complete the repair. To do this, click the "Start" menu and select "(My) Computer", and then open the local disk folder (usually the C drive). Open the "Windows" folder and then open the "System32" folder. Open the "Catroot" folder and then open the "F750E6C3-38EE-11D1-85E5-00C04FC295EE" folder. Delete any files that begin with "tmp". Your computer may not recreate the catroot2 folder immediately; expect to see it replaced after either rebooting or attempting to install Windows updates. Keep the renamed "oldcatroot2" folder until the new one is created; afterwards you may delete it.
Do not rename, move, or delete the catroot folder; it contains files necessary to recreate the catroot2 folder and keep the computer operating properly.