The answer is in the ConfuserEx Wiki Name Protection
Example:
<protection id="rename">
<argument name="mode" value="reversible" />
<argument name="password" value="This password is secret" />
<argument name="renameArgs" value="true" />
<argument name="renEnum" value="true" />
<argument name="flatten" value="true" />
<argument name="forceRen" value="false" />
<argument name="renPublic" value="false" />
<argument name="renPdb" value="true" />
<argument name="renXaml" value="true" />
</protection>
The important parts are mode
as reversible
and password
don't need explanation. All this in the .crproj file.
But if you want to use direct obfuscation declaration in class then use Declarative Obfuscation