Apps like WeChat take up a lot of space on your device. Only deleting the WeChat app does not clear WeChat data on your device.
From your Phone Settings (),
1.Go to Apps & Notification
2. Select WeChat from your installed App Info list
3. Go to Storage & Cache
4. Tap on CLEAR STORAGE
5. Select OK to confirm deleting app data
How to Delete WeChat from your Android Device
The process to UNINSTALL an App may differ on various Android versions although most would have similar process as shown here.
Once you Clear Storage,
6. Click on back arrow on top left to go to App Info screen
7.Tap on Uninstall
8. Select OK to confirm uninstalling the app
There are other options to uninstall an app from your Android device. You can TAP + HOLD & REMOVE or UNINSTALL from the Playstore.
Disclaimer: Your personal information and all of your written and communication via WeChat will remain in the Tencent server (and therefore likely be accessible by the Chinese government) even after the app is deleted from your device and/or you stop using or shutdown your account. Any data (i.e: posts, texts, audio messages, contacts etc) is also permanently on the TenCent server.