When searching for scans or web scans there is an option to mass update many of
them in a single click.
click on Show mass update on the right side above your scans list (marked with a red arrow in the picture below )
Then check the boxes of the scans or web scans you want to update and click on the mass update button marked in red in the picture below :
A new window will open in which you could delete/re assign/enable/disable run immediately etc. scans you have chosen