Definition: In this task, you need to remove all words of a given length in the sentence. The number of letters in a word determine its length, for example, the length of the word "apple" is 5.
Input: Sentence: 'a red stop sign says stop and then in small lettering is the word hating and power lines are in the background'. Remove all words of length '9' in the given sentence.

a red stop sign says stop and then in small is the word hating and power lines are in the background