How to remove all ODAC components from windows machine

1. Remove all oracle related entries from Environment variable path
2. Restart the machine
3. Stop all the services which is starting with ora or Ora
4. Run regedit.exe and delete the HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE key. This contains registry entries for all Oracle products.
5. Delete any references to Oracle services left behind in the following part of the registry: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Ora* It should be pretty obvious which ones relate to Oracle.
6. If your machine is  64 bit then deleted the HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\ORACLE key from the registry.
7. Restart your machine
8. Delete the "C:\app" directory(while installing if you gave other name then you need to delete that)
9. Delete the "C:\Program Files\Oracle" directory.
10. Empty the contents of temp directory ( use Window+R and then enter temp and clear date then %temp% then clear those data also) 
11. Empty the recycle bin.

Note 1: 

If we have installed ODAC with ODT new versions( 12.2 +) then we need to do couple of other steps to complete the full uninstallation of oracle products

Close all instances of Visual Studio

For Visual Studio 2015:

Please delete registry key HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\VisualStudio\14.0\Packages{D601BB95-E404-4a8e-9F24-5C1A462426CE}

For Visual Studio 2017 Enterprise:

CD into ( from command prompt)

C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Common7\IDE(if your VS is installed in some other path then, you have to go to that path)

execute:

VSIXInstaller.exe /skuName:Enterprise /skuVersion:15.0 /quiet /admin /uninstall:Oracle.VsDevTools.15.0

For VS2017 Professional:

CD into

C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE

execute:

VSIXInstaller.exe /skuName:Pro /skuVersion:15.0 /quiet /admin /uninstall:Oracle.VsDevTools.15.0

For VS2017 Community:

CD into

C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE

execute:

VSIXInstaller.exe /skuName:Community /skuVersion:15.0 /quiet /admin /uninstall:Oracle.VsDevTools.15.0

Note:

Above examples assume that VS2017 is installed at C:\Program Files (x86)\Microsoft Visual Studio\2017.

If you installed VS2017 into a different location, CD into the appropriate location and then execute the VSIXInstaller.exe command.

Note 2 : 

If you have already installed odp.net components then there might be an entry in the machine config. For safe side its better to remove it from there also. Do not remove any item which is started with System. which is not part of the odac components. ( Example : system.data.oracleclient)