The Microsoft SQL server or MSSQL is a database constructed by Microsoft for its popular operating system, Windows. If you wish to delete the program, you can simply do it through the Add/Remove Programs in the Control Panel. But in some cases, there could be corrupted registry that would prevent this process from being successful. It becomes even more impossible when there have been failed attempts at removing it. Another route is to perform a series of removal steps and they are done manually. The last step would entail an overall MSSQL delete as well as its server directory.

To start the process, halt all programs running in the MSSQL server. Go to Start and click Settings. From the Control Panel window, double-click the Services icon. If you see SQLServerAgent or MSSQLServer, highlight and then click Stop.

Next, launch the Windows Registry by going to Start and then selecting Run. From the box provided, enter "regedit" and select OK. This will open the Windows Registry Editor. This is where you can navigate all entries and modify or delete them. Look for the plus sign next to HKEY_LOCAL_MACHINE and expand it. Then navigate to Software and System to look for MSSQL Server. Your goal is to delete these keys by right- clicking the names and choosing "Delete". MSSQLServer is usually found under Microsoft, CurrentControlSet and Services. If your server will allow it, also check System and then remove any existing MSSQLServer around.

The next step would involve cleaning system variables. To do this, look for the My Computer icon and right click this option. Go to Properties and select Environment. This will launch a box where you can see System Variables. Look for any traces of MSSQL and delete them.

Now that you have manually deleted the entries, you can begin completely uninstalling the SQL Server. It is often found on the C: drive. Once you have found the folder, simply right click the option and select Delete. Click OK when the system asks you for confirmation. Make sure to reboot your computer for the changes to take into effect. If you aren't sure about any of these steps, check online guides or ask a trained technician.