Its very simple you need to become root by this command
sudo - i // to become root
Now cd to the file path like example below :
cd /path/to/file path
Now we can change permission by this command :
chmod +x filename.sh
Now you can simply run .sh file like
If you want to change the user so you can switch user like :
sudo -i -u username // username is the user by which you are logged in.
In case of any query please comment.