Is it considered an act of disbelief (kufr) not to remove complete newspaper pages from the sewers, knowing that intentionally disrespecting the name of Allah is an act of disbelief, and does the ruling differ if the bundles are large?

It is obligatory to protect anything containing the name of Allah from desecration, provided it does not cause undue hardship. People should be advised against using anything that involves desecration.

One who leaves papers containing the name of Allah as described does not commit an act of disbelief (kufr), nor is it considered a sign of embracing disbelief.

This question indicates obsessive doubts (waswasah). It is recommended to consistently make supplications and consult a psychiatrist.