Reinstall sp2013

I have a simple 3 server farm. I would like to reinstall SharePoint on existing servers. I am not sure of the steps involved and could use some guidance. There is no search or mms. There are no Excel services either. I use hosted applications that are hosted locally on my network.
When I initially installed the farm, I used very slow units. There were problems from the beginning because of this.
I am thinking that you should unmount the content databases and manually rebuild the services and reread the trust in our hosted application server.