Simple answer: you ignore it.
But, taxes aren't simple.
There's pre tax reimbursement and after tax reimbursement.
By law your employer can only give you $5250 maximum, tax free. If your tuition was less than that, and you employer reimbursed it all; it’s safe to assume nothing needs to be reported. You do not even need to enter your 1098-T. You have nothing to claim.
If you got more than $5250, the amount above $5250 is usually already included in box 1 of your w-2 and you do not need to enter anything additional on your tax return. Since you have essentially paid tax on that part, it is considered your after tax money and any amount over $5250 can be used to claim the tuition credit.
If you paid tuition in 2019, but the reimbursement wasn't paid to you, until Jan 20; you have a choice (actually a tax loop hole). You can claim nothing on your 2019 tax return, since it will be reimbursed in 2020. Or, you can claim a tuition credit, because you are out-of-pocket. But, then you'll have to report your 2020 reimbursement as taxable income.
