State tax filing

First, go through CA. Allocate all income as CA or not. Enter the rental property income/sale as CA income.

Under Residency Information, you have a choice between dates of residency or residency ratio.

The capital gain was received while a resident of CA so it will go on the CA return. This will be entered in Allocating Capital Gain and Loss.

You need to know the tax liability on this amount. 

1. I recommend you enter this as zero amount, look at the tax liability.
2. Then enter the sale amount and look at the tax liability.
3. Subtract to find the tax on just the sale amount.

Second, go through UT. Allocate all income as UT or not. 

1. Continue through until you reach Credit for Tax Paid to Another State. 
2. Select Work on Credit.
3. Select CA, continue
4. Enter double taxed income. I do realize it says while a Utah resident. If you had remained a CA resident all year, you would be paying tax to UT with a credit on CA. However, you moved to Utah so CA is getting the tax and UT is giving you the credit, you are now a Utah resident with the tax burden.
5. Enter the tax liability on the income that you determined above while in CA.

Here are CA screenshots

Here are Utah screenshots: