For the benefit of others, I found the note below to fix the issue
1745761 - Segmentation model is locked and generation still running
Stpes to fix the issue
1. Go to Transaction CRMD_MKT_TOOLS.
2. In the Segment Builder section, select 'Reset the "Being Generated" status of a given Segmentation Model'.
3. Use the F4 help to locate the Segmentation Model.
4. Execute to reset the status.