#!/bin/bash
s='http://domain/section1/section2/resource.html http://domain/section1/section2/resource1.html
http://domain/section1/section2/section3/resource2_4.html?param=param1 http://domain/section4/section5/resource3.html'
awk '{sub(/[^\/]+$/,"",$1)}1' <<< "$s"
IyEvYmluL2Jhc2gKcz0naHR0cDovL2RvbWFpbi9zZWN0aW9uMS9zZWN0aW9uMi9yZXNvdXJjZS5odG1sIGh0dHA6Ly9kb21haW4vc2VjdGlvbjEvc2VjdGlvbjIvcmVzb3VyY2UxLmh0bWwKaHR0cDovL2RvbWFpbi9zZWN0aW9uMS9zZWN0aW9uMi9zZWN0aW9uMy9yZXNvdXJjZTJfNC5odG1sP3BhcmFtPXBhcmFtMSBodHRwOi8vZG9tYWluL3NlY3Rpb240L3NlY3Rpb241L3Jlc291cmNlMy5odG1sJwphd2sgICd7c3ViKC9bXlwvXSskLywiIiwkMSl9MScgPDw8ICIkcyI=