[Tutor] String-manipulation question

[Alan Gilfoy]

#start of triple-letter processing block
if len(roman_input) > 2 and roman_input[0] + roman_input[1] +  
roman_input[2] == "MMM":
     digital_result += 3000
     roman_input = #something to remove those "M"'s from the string
     continue

-- 
My question here boils down to, "Is there a way to remove certain  
characters from a string?"

Here, I'm trying to set the variable roman_input (the string's name)  
equal to the string minus those characters, the 3 Ms. (being the first  
three characters  of the string, they would be roman_input[0],  
roman_input[1], and roman_input[2].)

Setting the (new) string equal to the (old) string minus those three  
characters will enable calculations on the string to keep running,  
because I have this piece of code, and similar pieces nested in a loop.