I assume you are talking about removing Tags field from Alfresco Explorer for the existing content, which is already applied with "Taggable" aspects.
1) First of all, remove that rule, so that it does not apply for future contents.
2) Using the same "Create Rule wizard", you can remove the Taggable Aspect by setting "Update" rule. (i.e.,) create rules for all the documents which are updated and update every document you have applied the taggable aspect.
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