well...the dead stuff looks like it already become dead for more than a month and very hard to cut it away.so,just leave it there.until the time u repotting it,pull it out
go buy some of those pesticides i recon u to buy from Mr. LIm.that pesticide works great for me.and u should always have some on hand incase those stupid pest(mealy bugs,scales etc bla bla bla) come
Thanks
Harris