I have disable my iPhone with my iCloud. How to enable

From the article below.

Turn off Lost Mode on an iPhone, iPad, iPod touch, or Apple Watch

1. In Find My iPhone on iCloud.com, click All Devices, then select the device that’s in Lost Mode.
2. Click Lost Mode, click Stop Lost Mode, then click Stop Lost Mode again.
3. You can also turn off Lost Mode by entering your passcode on the device.

Note: If you had any cards suspended when you put your device in Lost Mode (credit or debit cards for Apple Pay, or student ID cards or Express Transit cards), when you turn off Lost Mode and sign back in to iCloud, you can use them again.

Find My Phone - Lock and track your device using Lost Mode.  * 

Remove Activation Lock on the device.

Follow the onscreen steps to enter the Apple ID and password you used to set up your device or your device passcode.

Learn how to find your Apple ID or reset your Apple ID password.

Remove Activation Lock on the web if a device is offline.

1. Go to www.iCloud.com/find.
2. Sign in with your Apple ID and password.
3. At the top, click All Devices.
4. Select the device that you want to remove from iCloud.
5. Click Remove from Account.

Start a support request.

If you need help removing Activation Lock and have proof of purchase documentation, you can start an Activation Lock support request. 