According to Catholicism, can an imprimatur be revoked? According to Catholicism, can an imprimatur be revoked?

If so under what conditions are necessary to merit such a decision, if any.
According to Catholicism, can an imprimatur by revoked?

The short answer is yes.

Historically, it has happened on several occasions. The reasons also vary. 

It usually happens when Rome has received several complaints about a certain printed works (on paper or in modern times digital works).

First of all, what is an imprimatur?


  Imprimatur
  
  Definition
  
  The Latin term for "let it be printed," which signifies the approval by a bishop of a religious work for publication. Authors are at liberty to obtain the imprimatur either from the bishop where they reside, or where the book is to be published, or where it is printed. Generally the imprimatur, along with the bishop's name and date of approval, is to be shown in the publication. According to a decree of the Sacred Congregation for the Doctrine of the Faith (1975), "the Pastors of the Church have the duty and the right to be vigilant lest the faith and morals of the faithful be harmed by writings; and consequently even to demand that the publication of writings concerning the faith and morals should be submitted to the Church's approval, and also to condemn books and writings that attack faith or morals." (Etym. Latin imprimere, to impress, stamp imprint.)


An imprimatur is not a nihil obstat.


  Nihil Obstat
  
  Definition
  
  Approved by the diocesan censor to publish a manuscript dealing with faith or morals. The date of the approval and the name of the person approving (censor deputatus, delegated censor) are normally printed in the front of the book along with a bishop's imprimatur.


In 1996, the Holy See order the revoke of an imprimatur from the Psalms translated by the International Commission on English in the Liturgy. Rome takes things serious at times. Translations must meet with Rome’s standards.


  On August 6, Bishop Anthony M. Pilla of Cleveland, the president of the National Conference of Catholic Bishops, issued a decree withdrawing the US bishops’ imprimatur from the Psalms translated by the International Commission on English in the Liturgy.
  
  Bishop Pilla was acting on instructions conveyed in April 1996 by Cardinal Joseph Ratzinger, Prefect of the Congregation for the Doctrine of the Faith. The imprimatur is an official recognition that a work is suitable for publication.
  
  In his letter to bishops accompanying the decree, Bishop Pilla stressed that "the revocation of the imprimatur should in no way be perceived as a revocation of the judgment of the censors’ opinions concerning the fidelity or accuracy of the text", nor as a reflection on "the judgment of our bishops’ Ad Hoc Committee for the Review of Scripture Translations that recommended the granting of the imprimatur.” [Bishop Pilla’s letter and decree were published in Origins, Sept. 3 , Vol. 28:12, pp. 215.]
  
  Bishop Pilla said the decision to remove the imprimatur was due to "changing circumstances” according to which "the conference’s decision to grant the imprimatur is no longer considered appropriate or opportune.” He did not explain the two-year delay in acting on the Vatican’s instruction.
  
  The ICEL Psalter was published in 1995 by Liturgy Training Publications of the Archdiocese of Chicago, with the imprimatur of Baltimore Cardinal William Keeler, president of the NCCB.
  
  The imprimatur was granted after the text was approved by the bishops’ Committee for the Review of Scripture Translations. Members were Bishop Richard Sklba auxiliary of Milwaukee, chairman; Bishop Emil Wcela auxiliary of Rockville Centre; and Bishop Donald Trautman of Erie. (Bishop Trautman was then chairman of the Liturgy Committee.) - Holy See’s 1996 Order to Revoke Imprimatur Revealed in August


Wikipedia states that in 1980 three imprimaturs were revoked.


  If further examination shows that a work is not free of doctrinal or moral error, the imprimatur granted for its publication can be withdrawn. This happened three times in the 1980s, when the Holy See judged that complaints made to it about religion textbooks for schools were well founded and ordered the bishop to revoke his approval. Imprimatur (Wikipedia)


The following may be of some interest also:


Instruments of Social Communication and Books in Particular (Canon Law  822 - 832)
Vatican orders bishop to remove imprimatur.
The Catholic Church in World Politics
Eric O. Hanson · 2014 · Political Science
... Philip S. Keane's Sexual Morality without its imprimatur after Archbishop Hunthausen had been ordered to rescind it.