Like installing specialized rooms, removing the expansion that unlocks a theme or environment removes the corresponding theme/environment.
FYI:

• Blast Furnace is unlocked at 1F, Both Wings.
• Cooling Chamber is unlocked at 1F, Both Wings
• Falling Embers is unlcoekd at 2F, Single Wing
• Snowfall is unlocked at 2F, Single Wing
• Power Complex is unlocked at 2F, Both Wings
• Wasteworks is unlocked at 2F, Both Wings
• Rainfall is unlocked at 2F, Both Wings

~Guywhois95kpoorer