Try this:
@Model(adaptables = SlingHttpServletRequest.class)
public class ModelA {
private String title;
@Deleted Account
ModelB modelb;
}
Or if ModelB is adaptable only from Resource then
@Model(adaptables = SlingHttpServletRequest.class)
public class ModelA {
private String title;
@Deleted Account
@Via("resource")
ModelB modelb;
}