The deadline for obtaining a return of this excess contribution before the due date of your tax return was October 15, 2019, a date that has passed. You must file an amended 2018 tax return with amended 2018 Form 8889 to report the $2,633.33 excess contribution and pay the 6%, $158 excess contribution penalty. Since you will never again be eligible for an HSA contribution which would allow you to apply the excess as a subsequent year, to avoid another penalty of 6% on the lesser of the $2,633.33 or the 2019 year-end balance in the HSA you need to either take a taxable distribution of the $2,633.33 or fully deplete the HSA by the end of 2019.
A taxable distribution in 2019 is made by taking it out of the HSA and not claiming it on 2019 Form 8889 as having been applied to a qualified medical expense (even if you actually did spend it on a medical expense). Presumably you are age 65 or over, so a taxable distribution will not be subject to any early-distribution penalty, just to income tax.
As I mentioned, since the 6% penalty is calculated on the greater of the amount of excess or the year-end balance in your HSAs, so fully depleting your HSA nontaxably by applying it all to qualified medical expenses (as an alternative to or in combination with making a taxable distribution of the excess) will result in an excess contribution penalty of 6% of $0 even though the excess technically remains.
