Reconfiguring FreeBSD Ports – Remove OPTIONS config For Any Port

While building Apache port I was presented with a menu from which I selected certain build options. However, certain option giving out error as follows: ===> apache-2.2.8 mod_mem_cache requires WITH_THREADS. *** Error code 1 All I wanted to do is disable mod_mem_cache and build Apache again. Unfortunately, it is not allowing me to clear out configuration option. How do I remove all selected options and allow me to start over again?

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