Hi,
export the field in an unmanaged solution. Extract the solution. Open the customization.xml in best case an text editor (notepad++ with xml extension) or Visual studio, but also notepad will do the job. Look for the color code and remove just the Hexa color code not the color xml.
Before:
<option value="100000002" ExternalValue="" Color="#0000ff">
<labels>
<label description="VMWare" languagecode="1033" />
</labels>
<Descriptions>
<Description description="" languagecode="1033" />
</Descriptions>
</option>
After:
<options>
<option value="100000000" ExternalValue="" Color="">
<labels>
<label description="Microsoft" languagecode="1033" />
</labels>
<Descriptions>
<Description description="" languagecode="1033" />
</Descriptions>
</option>
Zip it back to the same name of the solution as it was before. And import and publish.
That did the trick for me. Deletion of the whole xml statement will not work as it smoehow does not overwrite the existing settings.
Optionssets are allways a bit reluctand during deployments. When it does not appear later in managed environments. Make a small unmanaged change like change of the name and then remove the active layer. This usually sorta all correct.
I would only recommend changing XML of a solution, when you know what you are doning. Unwanted changes may lead to unexpected errors and are very hard to find then wichout the right backups and tools. But if you do it in a calm very focused manner it should be doable.
BR Torsten