Deductions & credits

Hi, 

Hi, I am leaving my current employer and I must pay back my relocation package to him that i got in 2019. If I pay back the full amount (included taxes Gross-Up – Federal, Gross-Up – FICA and Gross-Up – Medicare). How can I get a credit for those taxes gross-up? they are more 3K. they are including in my W2 as wage (line 1). Please provide help