Anyhow i found a trick to downgrade windows 7 ultimate to professional easily without the new installation.
Windows 7 ultimate to windows 7 professional downgrade.
Note a windows 8 customer who has multilanguage functionality cannot downgrade to windows 7 pro or to windows xp pro.
The time to complete the process should only be several minutes but the time will vary from computer to computer.
Download windows 7 downgrader.
Knowing you have windows 7 enterprise tells me this.
The trick should also work if you intend to downgrade from higher edition of windows 7 to lower edition such as from windows 7 ultimate to windows 7 professional or from windows 7 professional to windows 7.
The ultimate version is the higher version of windows 7 and it can t be downgraded to lower versions officially without formatting or doing a fresh installation.
If windows 10 just seems unstable you ll want to go back to your previous version of windows and wait a while longer before attempting an upgrade.
Unfortunately unless you went through an upgrade process there is no safe way to revert back to older editions.
If an important program or hardware device you use doesn t work on windows 10 you ll want to downgrade.
A windows 7 ultimate installation can normally not change into a minor version of windows 7 home premium or professional.
Next insert your windows installation disk select upgrade and your windows 7 enterprise will be downgraded to the version you have specified.
Continue with usual windows 7 installation procedure and let windows upgrade downgrade from windows 7 enterprise to target version.
7 finally click the go back to windows 7 and to begin the downgrade process.
Beta release candidate build 7100 or rtm build 7600 and want to install a cheaper version windows 7 home premium or professional the installation is refused.
Be aware that there are no downgrade rights to windows 7 ultimate.
Or if you d just rather hang onto windows 7 for a while longer you can downgrade.