As of February 16, 2019, instructors who are using Canvas’s New Gradebook (beta) will have the option of replacing a student’s final grade — as calculated by Canvas — with a manually entered grade. More information about Final Grade Override is available in Canvas’s February 19 feature release notes.
If you’re not currently using the New Gradebook (beta), it’s important to note that this tool is still in development and there are some limitations. Once certain features are used, including Final Grade Override, the New Gradebook can’t be disabled in that course. Learn more about enabling and using the New Gradebook (beta).