requireしたClassやModuleをunloadしたかったからremove_constで削除した

Object.send(:remove_const, :Target) でよさそう。

• Unload a ruby class - Stack Overflow

[1] 2.3.0-p0(main)> Test.class
NameError: uninitialized constant Test
from (pry):1:in `__pry__'
[2] 2.3.0-p0(main)> require "./test"
=> true
[3] 2.3.0-p0(main)> Test.class
=> Module
[4] 2.3.0-p0(main)> Object.send(:remove_const, :Test)
=> Test
[5] 2.3.0-p0(main)> Test.class
NameError: uninitialized constant Test
from (pry):5:in `__pry__'
[6] 2.3.0-p0(main)>