delete tool isn't working use truncate tool instead
Use delete tool to delete all rows.
Delete tool does not works, it did not delete any rows. It could be ArcPro bugs.
Delete tool not working is knowing bug click here
https://community.esri.com/t5/arcgis-pro-questions/unable-to-delete-features-with-delete-features-or/td-p/1313869
use truncate tool, it works, no bugs
Alternatively, you can use SQL server management studio to run SQL truncate table. Same as previous result.