How to clean Python file (numbers, patterns)?

I have a long text formatted this way:

2689 3015 worth n
1095 9183 worth prep
4659 1314 worthwhile a
4503 1394 worthy a
36 272345 would modal
3404 2077 wound n
4789 1263 wound v
3174 2319 wrap v
4257 1508 wrist n
223 41497 write v
1329 7309 writer n
1939 4727 writing n
2483 3390 written a
723 14274 wrong a
5771 930 wrong adv
5544 995 wrong n
5774 929 x-ray n
4424 1426 yacht n
1510 6360 yard n
5354 1056 yarn n

My question is: how do I delete all the numbers from such a file and leave only the words that are n, v, a and adv?

When I succeded in removing numbers, adding the lines from a file to a string, I got confusted how to use regex in that case and leave only the words I desire. The result should be:

worth
worthwhile
..

so, without the word-type-ending.

Should I try to obtain this by pasting those words into a .txt file? How would you do that?