Regular Expression can be used in replaceAll() String method to replace all the special characters from the string in Salesforce Apex.

In the following sample Apex code, I have removed all the special characters from the String. Instead of ”, you can use a replacement character if you have a requirement to replace it with some character.

Sample Apex Code:

String tempStr = 'Infallible-Techie@!#$%^&*()_-+=Testing';
tempStr = tempStr.replaceAll( '[^a-zA-Z0-9]', '' );
System.debug(
    'tempStr is ' +
    tempStr
);