You delete text by using the Delete key. Quite often, the Backspace key is mapped to do the same thing, but not always. The C-D combination can also delete characters.
As with other commands, the Meta (Escape or Alt) key works in a similar manner. M-Delete deletes the word to the left of the cursor, M-D deletes the word to the right. The combination C-K ``kills'' from the cursor to the end of the line, and M-K kills from the cursor to the beginning of the line.