Hello, is it possible to know where a rules is used? I want to cleaning my

You can find the UUID of the rule by exporting the rule and looking at the XML from the downloaded package. Once you have the UUID, you can package all the process models, dashboards, pages, reports, rules, records and tempo reports into and export the package. Download the zip and extract it. Then using a text editor like Editplus or Notepad++ do a Find in Files on the whole application folder that you just extracted and look for the UUID of your rule. This should help you in finding all the artifacts where the rule is used.

FYI - In Appian 7.3, you have the concept of Rule dependency checker that shows all the places where the rule is used both up-chain and down-chain.

Great! Sathya this is a good news. We'll planning to upgrade to 7.3 because for the moment we have 6.6.1 (and it's not supported and very old :) )