Many thanks.. here is what happened when I tried to uninstall proftpd and install the other package instead:
LOL
# yum remove psa-proftpd psa-proftpd-xinetd
Resolving Dependencies
--> Running transaction check
---> Package psa-proftpd.x86_64 0:1.3.6-11.el7.art will be erased
--> Processing Dependency: psa-proftpd >= 1.3.4d for package: plesk-web-hosting-17.8.11-cos7.build1708180301.19.x86_64
--> Processing Dependency: psa-proftpd >= 1.3.4d for package: plesk-web-hosting-17.8.11-cos7.build1708180301.19.x86_64
---> Package psa-proftpd-xinetd.x86_64 0:1.3.6-11.el7.art will be erased
--> Running transaction check
---> Package plesk-web-hosting.x86_64 0:17.8.11-cos7.build1708180301.19 will be erased
--> Processing Dependency: plesk-web-hosting >= 17.8.11 for package: psa-horde-5.2.17-cos7.build1708180425.15.noarch
--> Processing Dependency: plesk-web-hosting >= 17.8.11 for package: plesk-roundcube-1.3.6-cos7.build1708180427.13.noarch
--> Running transaction check
---> Package plesk-roundcube.noarch 0:1.3.6-cos7.build1708180427.13 will be erased
---> Package psa-horde.noarch 0:5.2.17-cos7.build1708180425.15 will be erased
--> Processing Dependency: psa-horde >= 5.1.6 for package: psa-ingo-3.2.16-cos7.build1708180425.15.noarch
--> Processing Dependency: psa-horde >= 5.1.6 for package: psa-turba-4.2.21-cos7.build1708180425.15.noarch
--> Processing Dependency: psa-horde >= 5.1.4 for package: psa-passwd-5.0.7-cos7.build1708180425.15.noarch
--> Processing Dependency: psa-horde >= 5.1.6 for package: psa-mnemo-4.2.14-cos7.build1708180425.15.noarch
--> Processing Dependency: psa-horde >= 5.1.6 for package: psa-kronolith-4.2.23-cos7.build1708180425.15.noarch
--> Processing Dependency: psa-horde >= 5.1.6 for package: psa-imp-6.2.21.1-cos7.build1708180425.15.noarch
--> Running transaction check
---> Package psa-imp.noarch 0:6.2.21.1-cos7.build1708180425.15 will be erased
---> Package psa-ingo.noarch 0:3.2.16-cos7.build1708180425.15 will be erased
---> Package psa-kronolith.noarch 0:4.2.23-cos7.build1708180425.15 will be erased
---> Package psa-mnemo.noarch 0:4.2.14-cos7.build1708180425.15 will be erased
---> Package psa-passwd.noarch 0:5.0.7-cos7.build1708180425.15 will be erased
---> Package psa-turba.noarch 0:4.2.21-cos7.build1708180425.15 will be erased
^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C