Given a string and a character, write a Python program to replace multiple occurrences of the given character by a single character.

Here's a Python program that replaces multiple occurrences of a character with a single occurrence: 

# function to remove multiple occurrences of a character
def remove_duplicates(s):
    if len(s) < 2:
        return s
    result = s[0]
    for i in range(1, len(s)):
        if s[i] != s[i-1]:
            result += s[i]
    return result

# test the function
s = "abbcccddddeeeee"
result = remove_duplicates(s)
print(result)

This program defines a function called remove_duplicates that takes a string s as input and returns the string with multiple occurrences of a character replaced by a single occurrence. The function works by iterating over the characters of the string and appending each character to a result string if it is different from the previous character.

In the main part of the program, the function is called with a test string "abbcccddddeeeee" and the result is printed to the console. The output of the program should be the string "abcde".