Someone owed me money and he wanted to pay me in Bitcoin.
So I gave him my Bitcoin wallet address and he transferred the funds.
It's now complete.
But can he now withdraw the money since he has my bitcoin wallet address?
It's a No...
You're the only who has access to your Bitcoin, except of course maybe your account is been compromised, or you shared your wallet secret phrases with him, but if you didn't , then you're sure that your funds are safe and can't be accessed by either your friend or someone else.
And if you're concerned about your Bitcoin's safety and security, perhaps this thread may be of help to you
https://bitcointalksearch.org/topic/bitcoin-security-and-safety-5312045It may worth mentioning that anyone who knows your bitcoin address can check your transactions.
So, if you care about your about your privacy, you shouldn't reuse addresses.
Yes, and this helps maintain transparency in the Bitcoin Network, although it might look like this feature makes Bitcoin users not to enjoy complete anonymity and make Bitcoin transaction traceable and every man's business. Although there are some anonymous wallets that are not easily trackable even when you have the wallet addresses.
And OP you made a little typo error in your statement.