First and foremost to Barrys succeeding, he needs to get back to the past Central City and make sure that hes not seen. Then he needs to take down his past self in order to take on his identity for a short while.
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So, that plan is thrown completely out of the window within seconds of present/future Barry landing in his old life. Yep, near-enough as soon as he arrives, he gets spotted by his former self during the ongoing fight with Pied Piper.
WTF Barry! Seriously! But this was just the first of several ways in which Barry Allens plans would fall apart.