You can omit the preposition in this phrase.
The explanation of the event was omitted for lack of space.
You should omit this word from the sentence.
You can omit the last chapter of the book.
You omitted telling me to buy bread.
We'll sing that song, omitting the last two verses.
My name is omitted from the list.
Time is short and we must omit some of the speeches from the program.
The teacher omitted the exercise on page 21 of the book.