#!/usr/bin/python
# -*- coding: utf-8 -*-
string=raw_input("Слово? ")
print string.translate(None,"ыи")

$./test-ru.py 
Слово? ыыыаааиии
���

#!/usr/bin/python
# -*- coding: utf-8 -*-
string=raw_input("Слово? ")
print string.translate(None,"ыи").encode('utf8')

$ ./test-ru.py 
Слово? ыыыаааииии
Traceback (most recent call last):
  File "./test-ru.py", line 4, in <module>
    print string.translate(None,"ыи").encode('utf8')
UnicodeDecodeError: 'ascii' codec can't decode byte 0xb0 in position 0: ordinal not in range(128)

lst_char = u'ыи'
dict_chars = {ord(c): None for c in lst_char}
s = raw_input().decode('utf-8')
print(s.translate(dict_chars))