Hitler talked about conquered territories, not about Germany.
The Allies, including USA, disarmed and prohibited private gun ownership in conquered Germany in 1919 and then again in 1945. So the Allies did the same thing that Hitler was talking about.

The Hitler government actually RELAXED the earlier democratic gun laws from 1928 with the new Weapons Act of 1938.

The Weapons Act from 1938 had these differencies from the earlier 1928 law:

Long guns and ammunition for them were now deregulated, no permits needed.

The age limit for buying firearms was lowered from 20 to 18.

Government workers, hunters with the annual hunting permit and NSDAP members did no longerneed permits for handguns.

The firearms carry permit was valid for three years instead of one year.

Jews (they were no longer german citizens since 1935) could no longer manufacture or deal with firearms.

In 1945 the Allies prohibited all private gun ownership in Germany, and it wasn't until 1956 that germans could buy and own guns again, now with strict control. The gun laws during the Third Reich period were very liberal compared with those today in most of Europe.