How to transfer my old iCloud data into my new iCloud account ?

Hi kohlton129,

In this case you'll need to sign out of your account that you want to migrate data from, keep it on the device, and sign into your new account. Here's how:

"Sign out on your iPhone, iPad, or iPod touch

1. Go to Settings, then tap your name. 
2. Scroll down to the bottom.
3. Tap Sign Out.
4. Enter your Apple ID password and tap Turn Off. Forgot your Apple ID password? 
5. Turn on the data that you want to keep a copy of on your device.
6. Tap Sign Out.
7. Tap Sign Out again to confirm that you want to sign out of iCloud."

You can take a look at the full resource here: Sign out of iCloud on your iPhone, iPad, iPod touch, Apple TV, or Mac - Apple Support

We hope this helps.

Take care.