Once you have deployed the Azure Function in the Azure Portal from Visual Studio Code, You can able to open that Azure Function again using Visual Studio Code or Visual Studio IDE, If you want to edit the Existing Azure Function again.
Edit existing Azure Function in Visual Studio Code
You need to follow the below steps to do open existing Azure Function in Visual Studio Code.
Step-1: Login to Azure Portal (https://portal.azure.com/)
Step-2: Navigate to Function App that you have Deployed. Click on the one that you want open with Visual Studio Code or VisualStudio.

Step-3: Once you click on the Function App, Click on the Switch to classic experience and then click on the Continue to classic experience button.

Step-4: Now click on the Download app content button to download the your Function app content.

Step-5: Now on the Download app content project window, select the Content and Visual Studio project option, and then click on the Download button.

Step-6: It will prompt you to save the app content zip file in your local path. You can Unzip that file and try opening the folder in your Visual Studio Code or Visual Studio IDE.

You may also like following the below articles
Voila !! it is so easy to edit existing Azure Function in Visual Studio Code using the above information mentioned in this article. Thanks for reading this article !!!

I am Rajkishore, and I have over 14 years of experience in Microsoft Azure and AWS, with good experience in Azure Functions, Storage, Virtual Machine, Logic Apps, PowerShell Commands, CLI Commands, Machine Learning, AI, Azure Cognitive Services, DevOps, etc. Not only that, I do have good real-time experience in designing and developing cloud-native data integrations on Azure or AWS, etc. I hope you will learn from these practical Azure tutorials. Read more.