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.

Example Input: Sentence: 'a group of people skiing down the side of a snow covered slope'. Remove all words of length '7' in the given sentence.
Example Output: a group of people skiing down the side of a snow slope

Example Input: Sentence: 'a couple of airplanes sitting outside of a building'. Remove all words of length '1' in the given sentence.
Example Output: couple of airplanes sitting outside of building

Example Input: Sentence: 'a group of people ski on a snowy slope'. Remove all words of length '6' in the given sentence.
Example Output:
a group of ski on a snowy slope