Change branch base

I’ve a tree like this:

(commit 1) - master
                \-- (commit 2) - (commit 3) - demo
                                                \-- (commit 4) - (commit 5) - PRO

and I have to move the PRO branch to master

(commit 1) - master
                |-- (commit 2) - (commit 3) - demo
                \-- (commit 4) - (commit 5) - PRO

I’ve tried a git rebase master from PRO branch, but nothing happens.

To clarify: I was working in master and then I had to make a product demo (git checkout -b demo and some commits). Then, by mistake, I create another branch from demo (git checkout -b PRO and some commits) and now I need to move PRO branch to master and leave demo intact. At the end, both demo and PRO will hang from master.