In webmail. there are boxes tothe left of the envelope symbols.
You can check mark individual lines, or you can hit the check mark at the VERY top and that checkmarks all of them at once, and then you can hit delete.
If you want to display more emails at one time, you can click on settings at the top under the red verizon bar, and under the diplay listing (under general settings) you have "number of messages per page, and mine is set to no limit, but you can adjust that to be whatever you like, 20, 30, 40 etc.
