to edit datablock header and unit go to review & sign off tab, then

click on \'edit\' link for the datablock you wish to edit

change node title, unit, power of ten (unit multiplier), then click on verify and render to check the results and proceed to \'save\' button

to delete the datablock node use \'del\' link on review and sign off tab. The link is available only if there are no measurements associated with this datablock