Merging urls of the same site

Okay so here’s the problem
I have two major domains that I’m working with

monterey rainwater. com and monterey graywater. both .coms
This issue is with Monterey rainwater
Somehow is listed with the search engines under three different names
monterey rainwater. com
www.monterey rainwater. com
And http://www.monterey rainwater. com
the spaces in the urls is to comply with forum rules about how many urls may be present in this question
To further complicate things I have the website www.monterey
This website has a folder that contains an exact copy of the Monterey rainwater website.
I would just delete this folder but this copy is the one that is listed well with the search engines
So I’m just trying to combine them all so that Monterey graywater is its own site and all the different versions of Monterey rainwater are merged into one without losing my search engine ranking

@Midhuna I think 301 redirects are what you want. This link should get you started in the right direction.