While most people will tell you to just use multiple repositories, I feel it’s worth mentioning there are other solutions.
Solution 1
A single repository can contain multiple independent branches, called orphan branches. Orphan branches are completely separate from each other; they do not share histories.
git checkout --orphan BRANCHNAME
This creates a new branch, unrelated to your current branch. Each project should be in its own orphaned branch.
Now for whatever reason, git needs a bit of cleanup after an orphan checkout.
rm .git/index
rm -r *
Make sure everything is committed before deleting
Once the orphan branch is clean, you can use it normally.
Solution 2
Avoid all the hassle of orphan branches. Create two independent repositories, and push them to the same remote. Just use different branch names for each repo.
# repo 1
git push origin master:master-1
# repo 2
git push origin master:master-2