import re
test_str = "Param(\n [Parameter(Mandatory)]\n [String]$TaskName,\n [Switch]$Debug = $false\n)\n\n# Debug\nif ($Debug)\n\nParam(...)"
print (re.sub(r"^\s*Param\(.*?\)$", '', test_str, 0, re.M|re.S))
aW1wb3J0IHJlCnRlc3Rfc3RyID0gIlBhcmFtKFxuICAgIFtQYXJhbWV0ZXIoTWFuZGF0b3J5KV1cbiAgICBbU3RyaW5nXSRUYXNrTmFtZSxcbiAgICBbU3dpdGNoXSREZWJ1ZyA9ICRmYWxzZVxuKVxuXG4jIERlYnVnXG5pZiAoJERlYnVnKVxuXG5QYXJhbSguLi4pIgpwcmludCAocmUuc3ViKHIiXlxzKlBhcmFtXCguKj9cKSQiLCAnJywgdGVzdF9zdHIsIDAsIHJlLk18cmUuUykpCg==