[Refactoring] Remove unused variable from Hours

[rkowase]

Issue

• n/a

Overview (Required)

In this PR, I removed unused variable from Hours to fix a lint warning. I'm not sure anyone plan to use this unused right variable in the future, but I think it should be removed for now as _YAGNI principal_.

Links

• n/a

Screenshot

[takahirom]

Looks good!