An application should not be removed by simply deleting the folder into which it was installed. This is because an application often stores files in other folders as well as the one into which it was installed. Applications may also make entries into the system registry that should also be deleted when the application is removed.
The correct way to remove an application is to un-install it. This is done from the Add/Remove Programs panel, as follows:
If the application is not listed in the Add/Remove Programs panel, then it may be that it has a standalone un-install program. Look in the Windows Start menu to see if the application has an entry that contains an un-install program.
If you can not find an un-install program for the application, then you have no choice but to remove it manually, by deleting the folder into which the application was installed. However, only remove it this way as a last resort