First of all once you creates a site collection then you cannot change the template.
In this sitution you have two options.
- create new site collection using the correct template then move the content.
- use 3rd party tools create new site collection and move the content...i,e sharegate or metalogix etc...they have trial version.
The publishing site with workflow template is used similarly to the publishing site template to create sites designed to present web-based content. However, The publishing site with workflow template extends these capabilities by provisioning the resources need when content must be approved before it is made available to site users.once you create a site from this template you can configure the appropriate approval workflow to manage the content approval process.
The approval workflow is enabled by default only in the Publishing Site with Workflow site template. It can be used for content approval on a Web Site or an Intranet solution where the content must be reviewed before publication.
Now I think just enable the approval workflow on your sites so that nothing published without apporaval. That's mean you are using Publishing site with workflow.