If you have Anaconda in your PATH (check the output of echo $PATH to find out), remove it from your PATHand start Sage for the first time. To remove Anaconda from your PATH, you could either temporarily move the location of Anaconda (see the answer to Stack Overflow question 38175159) or change your PATH (see answer to Ask Sage question 35132). The above links can be found via a web search engine query for the error message in quotes together with the word sagemath. If you have Anaconda in your PATH (check the output of echo$PATH to find out), remove it from your PATH and start Sage for the first time.
To remove Anaconda from your PATH, PATH, you could either temporarily move the location of Anaconda (see the answer to Stack Overflow question 38175159) or change your PATH PATH (see answer to Ask Sage question 35132).
After you've started Sage once, I think it's okay to have Anaconda back in your PATH.