Delete (non-retrievable)/ kill (retrievable)

Character:

   1. C-d forward delete a character
   2. Delback backward delete a character

Word:

   3. M-d forward kill a word
   4. M-delback kill the word immediately before the cursor

Line:

   
   5. C-k  kills upto the end of the line
         not including the newline charcacter
   6. C-u 0 C-k  kills upto the beginning of the line
        not including newline character
        (You may replace "C-u 0" by "M-0", too)

Sentence:

 
   7. M-k  kills upto the end of the sentence
   8. C-u -1 M-k kills upto the beginning of the current sentence

Region:

   
   9. C-spc Set a mark at the current cursor position
  10. C-w kill the region between the current cursor position and
      the previous mark set by C-spc.

Undo

   1. C-x u
   2. C-_
   3. C-/

Yank

   2. C-y yank previous kill
   3. M-y replace text inserted by previous C-y by the next entry in the "kill ring".

N.B.

      1. M-5 C-/ undo last 5 changes
      2. M-2 C-y Yank last kill 5 times
      3. C-x C-s Save all the changes in the current file.