Ingrid Andress has slashed some of her upcoming shows in the aftermath of her National Anthem disaster -- and it appears to be directly related to her saying she's hitting rehab.
The country singer was set to perform at Nashville's Row One on Wednesday night and then at Denver's Globe Hall the following Wednesday -- but tickets are now unavailable, and the dates have been completely wiped from her website.
Ingrid's majorly scaling back her slate of upcoming performances -- by half, in fact -- 'cause the next time she's set to perform after these 2 nixed gigs is in Minneapolis on Aug. 3 ... and then in Maryland on Oct. 4.
On its face, it appears Ingrid's sticking to her word and getting the help she needs -- after saying in a statement, "I'm not gonna bulls*** y'all, I was drunk last night. I'm checking myself into a facility today to get the help I need. That was not me last night."
As we reported ... Andress gave Fergie a run for her money with one of the most off-key, all-over-the-place "Star-Spangled Banner" renditions in recent years.
It was so bad, Derby participants looked like they were holding back giggles throughout the song. Now, she's officially stepping away to handle her business ... for something that ended up being far more serious than anyone initially thought.