Ive already submitted my 2020 tax return,but it looks like im supposed to pay in 4 installments over the next year using 1040-V.can i opt out of this and just pay it all?

[fanfare]

look again. the four payments are estimated tax for 2021.

[Mike9241]

the 1040 V is to accompany a check, money order that you send the IRS  for the balance due on the 2020 return. you can also ignore it and make the payment through the IRS website

https://www.irs.gov/payments 

you can also pay the estimates through the same site.  the alternative is to increase your withholding so the total withheld is equal to last year + the amounts on each of the 4 1040-ES

put another way if you don't make the estimate payments your 2021 withholding must be 90% of 2021 tax or 100% (110% if 2020 AGI over $150,000/$75,000 if MFS) to avoid penalties