Note the record number of each person.Go to Grouping, under Individual Search scroll down and select Empty, click on search. This will open up a result window with no individuals in it.Press F10 and enter record no. of first individual. This puts that individual in the Result window.Press F10 and enter record no. of second individual. You now have both individuals in the Result window. Select the one you want to retain. Leaving that open, go to Utilitis/Project/Combine Individuals. Following instructions in screen. You probably will want to check to remove the duplicate individual (or whatever wording it uses).Check the result, you might have duplicate birth, death, etc. records.Just delete the ones you do not want.
Just to be safe, backup you're data before doing this.