What should a person do if they find on the ground promotional flyers bearing the Beautiful Names of Allah, and they are so numerous that it is difficult to collect them?

It is not permissible to discard papers containing the ذكر الله (remembrance of Allah) due to the disrespect involved. The Muslim's duty in this regard is: not to treat with disrespect papers that contain the remembrance of Allah, to advise others not to discard any papers that contain the remembrance of Allah, and to pick up any papers he finds that contain the remembrance of Allah or a saying of the Messenger of Allah, peace and blessings be upon him. Then, he should burn them or bury them in pure ground. As for what cannot be picked up, there is no harm in leaving it.