Manolo Saiz, the cycling team director at the centre of a doping storm in Spain, has decided to quit.
Astana-Wurth, who took over sponsorship of the team formerly known as Liberty Seguros, announced Saiz's resignation in a short statement on Thursday.
Saiz was questioned by police in May as part of a large anti-doping probe.
Police said they had raided a number of addresses, finding a large quantity of medical supplies, such as anabolic steroids, and frozen packs of blood.
Liberty Seguros withdrew their sponsorship of the team shortly afterwards.
The Liberty team hit the headlines last year when Roberto Heras was banned for two years after testing positive for the banned blood booster erythropoietin (EPO) on his way to a record fourth victory in the Tour of Spain.
Heras protested his innocence, arguing first that there must have been a laboratory mix-up and then that the testing process for EPO was flawed.
Team president Manuel Pinera has already stepped down.
The Spanish government has said it is determined to crack down on doping in sport and has passed a draft law which will make it an offence for professional athletes to use, or be supplied with, banned substances.