【come away】 —

1. become detached from smth.:

• I pulled the rotten wood and it came away without difficulty.

2. leave a place or the company of others:

• We came away with the uneasy feeling that all was not well with their marriage.

【go away】 —

1. = 【come away】 2:

• His manner became so repellent that visitors went away moralizing on the absurdity of nouveaux riches….

2. (imper.) is used to rudely tell a person to be off:

• I’m tired of your constant complaints; 【go away】 and leave me in peace.

3. (of a newly-wed couple) leave the wedding guests and go on one’s honeymoon:

• Mary bought a very smart outfit to 【go away】 in.