Here's what worked for me. Your mileage may vary; fiddle at your own risk; subject to change without warning; other generic warnings.
(Windows 10 | Steam)
First, go to:
This PC > Documents > PGA TOUR > settings > 1234567890 > 123456
(I don't know how important the numbers are in the last two sub-folders so I replaced them with generic numbers of the same length. They were the only folders there.)
From here, there will be several folders named with seemingly random 8 digit hex values.
If you only have 1 character, delete (or move to a backup location) the folder that contains the DATA file with your character's career progression data (it should be the one that was modified last). You can peek inside the DATA file within that folder with Notepad. If there is a bunch of numbers you've got the right folder. If it's mostly empty, try looking at a different one. Once that is deleted or moved, start the game and you should be able to restart your career. Your other progress (character, skills, challenges, etc) should be unaffected.
If you have multiple characters, then you'll have to search inside of each DATA file to see which folder corresponds to which character (again, it should be one of the last few modified folders). Open in Notepad and press "CTRL + F" to search for your character's name. You may have to search multiple times: one for each character. Alternatively, you can manually scroll down until you start seeing names (it should be the first entry in the second data set within that file). Once you've found the correct one, delete or move that folder. Start the game and you should be good to go.