If there are problems with a Yoga 13 laptop keyboard during warranty, Lenovo service would handle the replacement of the part. The keyboard is not typically expected to be replaced by the customer during warranty.
There may be times when a customer needs to remove and replace the keyboard - when accessing the memory module, or adding a second mSATA drive, or perhaps replacing a worn keyboard at some point after the warranty has ended.. The Yoga 13 hardware maintenance manual contains detailed instructions on performing this task.
After powering off the system and removing the AC connection, you can begin removing the keyboard by gently inserting a flat plastic tool like this one and pry the keyboard slightly toward the front of the system and then up to release a series of plastic snaps / latches located along the top of the keyboard.
Metal tools like a screw driver or knife blade should not be used as they can scratch or gouge the plastic and could slip and cause injury.
With the keyboard removed, you can see the tabs on the keyboard bezel spaced at intervals. Here is one ( circled ) just above the left fan.
These clips snap into small sockets along the top edge of the keyboard. This is why to release them, you pry the keyboard down toward the front to move the socket away from the tab and then lever it up.
Here is a view of the top edge of the keyboard - you can see the circled pocket that engages the tab.
At the lower edge of the keyboard, there are tabs that fit into slots as shown below. When removing the keyboard, once the top is unlatched all the way across the keyboard can be slid upward releasing these tabs. Installation, would be the reverse, guiding these tabs into the slots.
Another consideration is that they keyboard is anchored at various points across the middle, with a series of tabs that fit into pockets in the sheet metal keyboard tray area and then slide into place when the keyboard is installed.
If you install the keyboard and find that it is bowed up in one place or there is a bouncy / spongey area, it is probably caused by one of these clips not being in place. If the clips do not align with the pockets properly, they will act as stand offs, keeping the keyboard from fitting properly (flat) in the system.
Here is a picture of some of the clips on the bottom middle area of the keyboard.
Note that these tabs are rotated in different orientations and to engage properly, they all need to be aligned and pressed down in the middle area across the keyboard while sliding it down into place. Applying gentle pressure on the ASDFGHJKL row during installation will probably help.
Here are some of the sockets that these tabs latch into. Likely the middle and right circles ones in the photo above will fit into these locations circled in the photo below.
Lastly, there are some sections of double sided tape applied at a few points on the keyboard tray. Depending on the age of the system when the keyboard is removed, these might need to be replaced to ensure the keyboard has a factory fresh, solid feel to it once reinstalled.