To solve this issue you have 3 different ways and they are:
Commit the change.
git commit -m "My message"
Stash it.
You can push changes and stack them up in reverse order.
To stash, type:
git stash
Do the merge, and then pull the stash:
git stash pop
Discard the local changes
using git reset --hard or git checkout -t -f remote/branch.
Discard local changes for a specific file
using git checkout filename.
I hope this helps.