I bought some bitcoin from coinbase.  I then tried to transfer the BTC to my electrum wallet.  Not knowing what mBTC was, I used acronymfinder.com and was told (incorrectly) that it was microBTC.  Accordingly, I attempted to transfer 1000x as much BTC from the Coinbase wallet to my electrum wallet.  The result is now that the entire amount of BTC that was in Coinbase at that time was transferred, but my electrum wallet says that there is a transaction still pending listing the larger amount.  What do I do about this pending transaction?

Parenthetically, I have bought more BTC since then which sits in Coinbase and has not been transferred.  So, the only practical effect of this pending transaction may be to be (anti-)cosmetic.  Should I cancel the erroneous transaction or what?