How to remove the end effective date from party tax profile configuration

Hi,

In error under party tax profiles : configuration options, the tax regime has been end dated by giving entering date in the field effective to date. How to undo this and make the regime active for the party profile.

i queried for the party tax profile which is at OU owning tax context level (party type)  and after clicking on update button,  I do not have the option of blanking out or taking out the date as the record is non editable.

Please advise.

Thanks

Mythson