You don't need to remove it. Those are so you can take the diaper off and then retape it later.
The blue tab is another set of tapes so the diaper an be resealed a second time. They are refastenable.
Those blue tapes, FTuga, are the primary tapes. When you put the diaper on, it's the blue ones that will hold to the plastic. But if the diaper becomes loose, you don't get it right the first time, of you need to take the diaper off, then you can separate the white tapes from the blue and put the diaper back on. Some people call this arrangement "second-chance" tapes, which pretty well sums things up. Without these, once you stuck the tapes in place, that would be it. With these, you get a second chance to adjust or reapply.
the part sticks to the diaper and the tape sticks to that so the diapers can be refastened if needed
Thank you, y'all!