import re
text = 'Wow.. :smiley_face: this is delicious!' # A string containing emoji
print( re.sub(r'(:[a-z_]+:)|[^\w\s]|_', r'\1', text) )
aW1wb3J0IHJlCnRleHQgPSAnV293Li4gOnNtaWxleV9mYWNlOiB0aGlzIGlzIGRlbGljaW91cyEnICMgQSBzdHJpbmcgY29udGFpbmluZyBlbW9qaQpwcmludCggcmUuc3ViKHInKDpbYS16X10rOil8W15cd1xzXXxfJywgcidcMScsIHRleHQpICkKIA==