Replace:
ANTISPAM_SYSTEM='spamassassin'
ANTIVIRUS_SYSTEM='clamav-daemon'
With:
ANTISPAM_SYSTEM=''
ANTIVIRUS_SYSTEM=''
in /usr/local/hestia/conf/hestia.conf
And in /etc/exim4/exim4.conf.template replace
SPAMASSASSIN = yes
SPAM_SCORE = 50
SPAM_REJECT_SCORE = 100
CLAMD = yes
With
#SPAMASSASSIN = yes
#SPAM_SCORE = 50
#SPAM_REJECT_SCORE = 100
#CLAMD = yes
restart exim4 service
And run apt remove clamav spamassassin