What did the Treaty of London of 1867 require Prussia to do in Luxembourg?

Under the Treaty of London of 1867, Prussia was required to withdraw its military garrison from the capital city of Luxembourg. Additionally, the treaty mandated that the city's extensive fortress, which had served as a bulwark for the German Confederation, be dismantled. These measures were part of a compromise reached by the great powers to ensure Luxembourg's status as an independent and perpetually neutral nation.21