CSV file editing special charcters to normal characters

Hello, I have 2 sets of CSV files with 4 language variations for each set making a total of 8 spreadsheet files. One set has 12,300 records per file and the other one has 124 records per file. I need for the ALL of the special language characters to be replaced/subsituted with normal (US-ASCII) characters in all files. There is a way to substitute special characters to normal( ASCII) character format and I need this applied to each spreadsheet. I pay on time and promptly check my feedback as an employer.